Engine start system minimizing mechanical impact or noise

ABSTRACT

An engine start system which may be employed in automotive idle stop systems. To start an engine, the system brings a pinion gear into engagement with a ring gear coupled to the engine and turns on an electric motor to rotate the ring gear through the pinion gear to crank the engine. When it is requested to start the engine during deceleration of the engine before stop thereof, the system thrusts the pinion into engagement with the ring gear and then turns on the motor to rotate the pinion gear, in other words, delays the activation of the motor until after the pinion gear has engaged the ring gear. This minimizes mechanical impact or noise arising from the engagement of the pinion gear with the ring gear and improves the reliability in engagement with the ring gear during the deceleration of the engine and durability of the system.

CROSS REFERENCE TO RELATED DOCUMENT

The present application claims the benefits of priority of JapanesePatent Application Nos. 2009-93044 filed on Apr. 7, 2009, 2009-139060filed on Jun. 10, 2009, 2009-192728 filed on Aug. 24, 2009, 2009-252889filed on Nov. 4, 2009, and 2009-286536 filed on Dec. 17, 2009,disclosures of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Technical Field of the Invention

The present invention relates generally to an engine start system whichmay be used in an idle stop system for automotive vehicles (also calledan automatic engine stop/restart system) which works to stop anautomotive engine automatically, for example, when the vehicle hasstopped at an intersection or due to a traffic jam and then restart theengine when the vehicle driver performs a given starting operation(e.g., release of the driver's foot from the brake pedal).

2. Background Art

Automotive vehicles equipped with an automatic engine stop/restartsystem (also called an idle stop system) designed to stop the engineautomatically when an output of the engine is not required and restartthe engine automatically when the engine output is requested areexpected to increase in order to reduce carbon dioxide emissions orincrease the fuel economy.

The idle stop system typically works to automatically cut a supply offuel to the engine to stop it, for example, when the vehicle stops at ared light at an intersection or in a traffic jam and then restart theengine when given restart requirements are met, e.g., the driver hasreleased the brake pedal and/or shifted a selector lever to a driverange in the automatic transmission. For example, Japanese Patent FirstPublication No. 2003-301765 discloses such an idle stop system.

The vehicle operator may require the start of the vehicle immediatelyafter the idle stop system has been activated to stop the engine, afterwhich the vehicle stops. In such an event, if it is impossible torestart the engine until it stops completely, which may causeinconvenience to trailing vehicles. This may lead to the discomfort ofthe vehicle operator. One of requirements the idle stop system is neededto meet is, therefore, to enable the restart of the engine duringdeceleration thereof before being stopped completely.

In order to meet the above requirement, Japanese Patent FirstPublication No. 2005-330813 teaches an idle stop system which, when anengine restart request is made during a period of time in which thespeed of the engine is decreasing before the engine stops completely,starts energization of a shunt coil to rotate a pinion gear and thenbrings the pinion gear into engagement with a ring gear installed on acrankshaft of the engine at the time when the rotation of the piniongear is synchronized with that of the ring gear.

Additionally, Japanese Patent First Publication No. 2007-107527 teachesan idle stop system designed to bring the pinion gear into engagementwith the ring gear when the speed of the internal combustion enginefalls in a range between given maximum and minimum speeds, and thedirection of rotation of the engine matches the forward direction of thecrankshaft of the engine.

The idle stop system of Japanese Patent First Publication No.2005-330813, as described above, requires the synchronization of thespeed of the pinion gear with that of the ring gear and thus has theproblem that the speed of the engine may drop before an engine starterstarts rotating, which results in failure in the synchronization in avery low engine speed range. Moreover, when the idle stop system cutsthe fuel to the engine, it usually causes the speed of the engine todrop rapidly and overshoot the zero. The engine then swings in thereverse and forward directions cyclically and eventually stops. In sucha speed range where the engine swings (which will be referred to as anengine swing range below), it is very difficult to synchronize the speedof the pinion gear with that of the ring gear. The engagement betweenthe pinion gear and the ring gear will also result in a great deal ofmechanical impact between them, which may cause the breakage of the ringgear.

The idle stop system of Japanese Patent First Publication No.2007-107527 is, as described above, designed to engage the pinion gearwith the ring gear only when the direction of rotation of the enginematches the forward direction of the crankshaft of the engine, thusrequiring a sensor to measure the direction of rotation of the engine.The system is inhibited from engaging the pinion gear with the ring gearwhen the engine is rotating in the reverse direction, thus resulting inan increased difficulty in engaging the pinion gear with the ring gearin the engine swing range.

SUMMARY OF THE INVENTION

It is therefore an object of the invention to provide an engine startsystem which is installed in a vehicle powered by an engine and designedto achieve engagement of a pinion gear with a ring gear of the engine torestart the engine during deceleration thereof until the engine stopsand to minimize mechanical impact or noise arising from the engagementof the pinion gear with the ring gear.

According to one aspect of the invention, there is provided an enginestart system which may be employed in engine-powered automotivevehicles. The engine start system comprises: (a) a motor which isenergized by supply of electric power from a battery through a motorcircuit to produce torque; (b) an output shaft which rotates whensubjected to the torque, as produced by the motor; (c) a pinion gearthrough which the torque, as produced by the motor, is transmitted to aring gear coupled to an engine; (d) a pinion movable body which ismovable along the output shaft together with the pinion gear; (e) apinion actuator working to move the pinion movable body to the ringgear; (f) a switching mechanism working to open or close main contactsinstalled in the motor circuit to cut or supply the electric power fromthe battery to the motor; (g) controller which controls operations ofthe pinion actuator and the switching mechanism when the engine isrestarted during deceleration of the engine prior to stop of the engine;and (h) delay means for delaying a second operation time that is a timewhen the switching mechanism is to be activated to close the maincontacts until after a first operation time that is a time when thepinion actuator is to be activated to move the pinion movable body whenthe engine is restarted. The delay means produces a time lag between thefirst and second operation times so as to close the main contactsthrough the switching mechanism to supply the electric power to themotor after the pinion movable body is moved by the pinion actuator toadvance the pinion gear from a rest position to a gear engagebleposition where the pinion gear is engageble with the ring gear, and thenthe pinion gear engages the ring gear.

The phrase “after the pinion movable body is moved by the pinionactuator to advance the pinion gear from a rest position to a gearengageble position where the pinion gear is engageble with the ringgear, and then the pinion gear engages the ring gear” does notnecessarily mean “after the pinion gear engages the entire width of thering gear completely”, but contains the meaning of “after the piniongear at least partially engages the width of the ring gear”.

As described above, when it is requested to restart the engine duringdeceleration of the engine before complete stop thereof, the enginestart system of this invention works to electrically or mechanicallydelay the second operation time when the switching mechanism is to beactivated to close the main contacts until after the first operationtime when the pinion actuator is to be activated to move the pinionmovable body. Specifically, after the pinion actuator moves the pinionmovable body, and then the pinion gear engages the ring gear at leastpartially, the switching mechanism is energized to close the maincontacts to energize the motor.

In other words, the switching mechanism does not close the main contactsto keep the motor deenergized during a period of time for which thepinion gear is moved from the rest position to the gear engagebleposition, so that the torque, as produced by the motor, is nottransmitted to the pinion gear until the pinion gear engages the ringgear.

Even if the pinion gear, as moved by the pinion actuator, has failed toengage the ring gear directly, that is, the end of the pinion gear hashit the end surface of the ring gear (usually, the probability that theend of the pinion gear hits the end surface of the ring gear is higherthan that the pinion gear is moved by the pinion actuator and thenengages the ring gear directly), the pinion gear will then engage thering gear at a certain angular position because the engine isdecelerating, so that ring gear is rotating at a lower speed. Thisenables the engine to be restarted quickly during deceleration of theengine before complete stop thereof. The motor is kept off until thepinion has engaged the ring gear, thus minimizing mechanical impact ornoise arising from the engagement of the pinion gear with the ring gearand improving the reliability in engagement with the ring gear duringthe deceleration of the engine and durability of the system.

In the preferred mode of the invention, the delay means sets the timelag between the first and second operation times to 30 ms. or more. Thisensures the stability of engagement of the pinion gear with the ringgear of the engine before the motor is energized to rotate the piniongear.

The pinion actuator may be implemented by a solenoid actuator whichproduces a first electromagnet. The switching mechanism may beimplemented by a motor on-off switch which produces a secondelectromagnet. The controller may be designed to control operations ofthe solenoid actuator and the motor on-off switch independently of eachother and has installed therein a delay function which makes up thedelay means. Specifically, the controller serves to control the order ofthe first and second operation times.

The delay means may alternatively be implemented by a delay circuitconnected to an excitation circuit which works to excite the motoron-off switch. This eliminates the need for controlling the operationsof the solenoid actuator and the motor on-off switch through separatelines, in other words, it permits a single line to be used to controlboth the solenoid actuator and the motor on-off switch.

The controller may change the time lag between when the engine isrequested to be restarted during the deceleration of the engine and whenthe engine is requested to be restarted after a complete stop of theengine. The normal start of the engine is achieved by brining the piniongear into engagement with the ring gear placed in a resting condition,thus enabling the motor to be energized substantially simultaneouslywith abutment of the end surface of the pinion gear on the end surfaceof the ring gear. Therefore, there is no need for lengthening a delaytime from the abutment of the pinion gear with the end surface of thering gear until the energization of the motor. The engine start systemof this invention may be designed to change the first and secondoperation times between when the engine is restarted during thedeceleration of the engine and when the engine is restarted when theengine is at rest.

The solenoid actuator and the motor on-off switch may be aligned inseries with each other in an axial direction thereof. This result in adecrease in area of an assembly of the solenoid actuator and the motoron-off switch projected in the axial direction as compared with whenthey are arranged radially thereof.

The solenoid actuator and the motor on-off switch may have casings,respectively, which are arrayed integrally in the axial direction as asingle piece and constitute a magnetic circuit. This results in adecrease in parts of the engine start system and improves the resistanceof the solenoid actuator and the motor on-off switch against externalmechanical vibrations.

The engine start system may further include a magnetic coil producing anelectromagnet when energized, a plunger which is movable along an innerperiphery of the magnetic coil in an axial direction thereof, and asingle electromagnetic switch designed to perform both an operation ofthe pinion actuator and an operation of the switching mechanismfollowing movement of the plunger. The time lag is provided by a plungerstroke that is a distance which the plunger moves from a time when theplunger starts to be moved by attraction, as produced by theelectromagnetic, until the main contacts are closed.

For example, the starter, as disclosed in Japanese Patent FirstPublication No, 2003-301765, as referred to above, is equipped with asingle electromagnetic switch designed both as the pinion actuator andas the switching mechanism. Specifically, the electromagnetic switch hasinstalled therein a plunger which is to be moved by attraction, asproduced by an electromagnet, to push the pinion gear and close the maincontacts simultaneously. A stroke of the plunger is so determined thatthe main contacts may be closed substantially concurrently with when theend of the pinion gear hits against the end surface of the ring gear.The delay between the closing of the main contacts and the hit of thepinion gear against the ring gear may be provided by lengthening thestroke of the plunger as compared with that in the conventionalstructure. In the above case, the value of the time lag between thefirst and second operation times is determined mechanically bylengthening the stroke of the plunger to a desired value.

The engine start system may be installed in a vehicle equipped with anidle stop system working to stop and restart the engine automatically.

According to the second aspect of the invention, there is provided anengine start system which comprises: (a) a motor which is energized bysupply of electric power from a battery through a motor circuit toproduce torque; (b) an output shaft which rotates when subjected to thetorque, as produced by the motor; (c) a pinion gear through which thetorque, as produced by the motor, is transmitted to a ring gear coupledto an engine; (d) a pinion movable body which is movable along theoutput shaft together with the pinion gear; (e) a pinion actuatorworking to move the pinion movable body to the ring gear; (f) aswitching mechanism working to open or close main contacts installed inthe motor circuit to cut or supply the electric power from the batteryto the motor; (g) a controller which controls operations of the pinionactuator and the switching mechanism when the engine is restarted duringdeceleration of the engine prior to stop of the engine; and (h) delaymeans for delaying a second operation time that is a time when theswitching mechanism is to be activated to close the main contacts untilafter a first operation time that is a time when the pinion actuator isto be activated to move the pinion movable body when the engine isrestarted. The delay means produces a time lag between the first andsecond operation times so as to close the main contacts through theswitching mechanism to supply the electric power to the motor after thepinion movable body is moved by the pinion actuator to advance thepinion gear from a rest position to a maximum movable position whereengagement of the pinion gear with the ring gear is to be achieved, andthen the pinion gear has engaged the ring gear.

When it is requested to restart the engine during deceleration of theengine before complete stop thereof, the engine start system of thisinvention works to electrically or mechanically delay the secondoperation time when the switching mechanism is to be activated to closethe main contacts until after the first operation time when the pinionactuator is to be activated to move the pinion movable body.Specifically, after the pinion actuator moves the pinion movable body,and then the pinion gear engages the ring gear at least partially, theswitching mechanism is energized to close the main contacts to rotatethe motor.

In other words, the switching mechanism does not close the main contactsto keep the motor deenergized during a period of time required by thepinion gear to move from the rest position to the gear engagebleposition, so that the torque, as produced by the motor, is nottransmitted to the pinion gear until the pinion gear engages the ringgear.

Even if the pinion gear, as moved by the pinion actuator, has failed toengage the ring gear directly, that is, the end of the pinion gear hashit the end surface of the ring gear (usually, the probability that theend of the pinion gear hits the end surface of the ring gear is higherthan that the pinion gear is moved by the pinion actuator and thenengages the ring gear directly), the pinion gear will then engage thering gear at a certain angular position because the ring gear isrotating at a lower speed. This enables the engine to be restartedquickly during deceleration of the engine before complete stop thereof.The motor is kept off until the pinion has engaged the ring gear, thusminimizing the mechanical impact or noise arising from the engagement ofthe pinion gear with the ring gear and improving the reliability inengagement with the ring gear during the deceleration of the engine anddurability of the system.

In the preferred mode of the invention, the delay means sets the timelag between the first and second operation times to 30 ms. or more,preferably 40 ms. or more.

The pinion actuator may be implemented by a solenoid actuator whichproduces a first electromagnet. The switching mechanism may beimplemented by a motor on-off switch which produces a secondelectromagnet. The controller may be designed to control operations ofthe solenoid actuator and the motor on-off switch independently of eachother and has installed therein a delay function which makes up thedelay means.

The delay means may alternatively be implemented by a delay circuitconnected to an excitation circuit which works to excite the motoron-off switch.

The controller changes the time lag between when the engine is requestedto be restarted during the deceleration of the engine and when theengine is requested to be restarted after a complete stop of the engine.

The normal start of the engine is achieved by brining the pinion gearinto engagement with the ring gear placed in a resting condition, thusenabling the motor to be energized substantially simultaneously withabutment of the end surface of the pinion gear on the end surface of thering gear. Therefore, there is no need for lengthening a delay time fromthe abutment of the pinion gear with the end surface of the ring gearuntil the energization of the motor. The engine start system of thisinvention may be designed to change the first and second operation timesbetween when the engine is restarted during the deceleration of theengine and when the engine is restarted when the engine is at rest.

The solenoid actuator and the motor on-off switch may be aligned inseries with each other in an axial direction thereof.

The solenoid actuator and the motor on-off switch may have casings,respectively, which are arrayed integrally in the axial direction andconstitute a magnetic circuit.

The engine start system may further include a magnetic coil producing anelectromagnet when energized, a plunger which is movable along an innerperiphery of the magnetic coil in an axial direction thereof, and asingle electromagnetic switch designed to perform both an operation ofthe pinion actuator and an operation of the switching mechanismfollowing movement of the plunger. The time lag is provided by a plungerstroke that is a distance which the plunger moves from a time when theplunger starts to be moved by attraction, as produced by theelectromagnetic, until the main contacts are closed. Specifically, thedelay between the closing of the main contacts and the hit of the piniongear against the ring gear is provided by lengthening the stroke of theplunger as compared with that in the conventional structure. The valueof the time lag between the first and second operation times isdetermined mechanically by lengthening the stroke of the plunger to adesired value.

The engine start system may be installed in a vehicle equipped with anidle stop system working to stop and restart the engine automatically.

According to the third aspect of the invention, there is provided anengine start system which comprises: (a) a motor which is energized bysupply of electric power from a battery through a motor circuit toproduce torque; (b) an output shaft which rotates when subjected to thetorque, as produced by the motor; (c) a pinion gear through which thetorque, as produced by the motor, is transmitted to a ring gear coupledto an engine; (d) a pinion movable body which is movable along theoutput shaft together with the pinion gear; (e) a pinion solenoidactuator which produce magnetic attraction to thrust the pinion movablebody toward the ring gear; (f) a motor on-off switch which opens orcloses main contacts installed in the motor circuit to cut or supply theelectric power to the motor; (g) a first relay disposed in an excitationcircuit which supplies electric power from the battery to the pinionsolenoid actuator; (h) a second relay disposed in an excitation circuitwhich supplies electric power from the battery to the motor on-offswitch; (i) a controller which electrically controls an operation of thepinion solenoid actuator through the first relay and an operation of themotor on-off switch through the second relay when the engine isrestarted during deceleration of the engine prior to stop of the engine;(j) a delay circuit which delays a second operation time that is a timewhen the second relay is to be energized until after a first operationtime that is a time when the first relay is to be energized when theengine is restarted; and (k) a single electric wire connecting with anoutput port of the controller, the electric wire having a first relaybranch line leading to the first relay and a second relay branch lineleading to the second relay through the delay circuit. The delay circuitproduces a time lag between the first and second operation times so asto close the motor on-off switch to supply the electric power to themotor after the pinion gear is moved by the pinion solenoid actuatorfrom a rest position to a gear engageble position where the pinion gearis engageble with the ring gear and then engages the ring gear or fromthe rest portion to a maximum movable position where engagement of thepinion gear with the ring gear is to be established and then engages thering gear.

When it is requested to restart the engine during deceleration of theengine before complete stop thereof, the engine start system of thisinvention works to electrically or mechanically delay the secondoperation time when the second relay is energized until after the firstoperation time when the first relay is energized. Specifically, thedelay circuit works to close the motor on-off switch to supply theelectric power to the motor after the pinion gear is moved by the pinionsolenoid actuator to the gear engageble position or the maximum movableposition and then engages the ring gear.

In other words, the main contacts are not closed to keep the motordeenergized during a period of time required by the pinion gear to moveto the ring gear and then engages the ring gear. Therefore, the torque,as produced by the motor, is not transmitted to the pinion gear untilthe pinion gear engages the ring gear.

Even if the pinion gear, as moved by the pinion solenoid actuator, hasfailed to engage the ring gear directly, that is, the end of the piniongear has hit the end surface of the ring gear (usually, the probabilitythat the end of the pinion gear hits the end surface of the ring gear ishigher than that the pinion gear is moved by the pinion solenoidactuator and then engages the ring gear directly), the pinion gear willthen engage the ring gear at a certain angular position because the ringgear is rotating at a lower speed. This enables the engine to berestarted quickly during deceleration of the engine before complete stopthereof. The motor is kept off until the pinion has engaged the ringgear, thus minimizing the mechanical impact or noise arising from theengagement of the pinion gear with the ring gear and improving thereliability in engagement with the ring gear during the deceleration ofthe engine and durability of the system.

The engine start system may be installed in a vehicle equipped with anidle stop system working to stop and restart the engine automatically.

According to the fourth aspect of the invention, there is provided anengine start system which comprises: (a) a motor which is energized bysupply of electric power from a battery through a motor circuit toproduce torque; (b) an output shaft which rotates when subjected to thetorque, as produced by the motor; (c) a pinion gear through which thetorque, as produced by the motor, is transmitted to a ring gear coupledto an engine; (d) a pinion movable body which is movable along theoutput shaft together with the pinion gear; (e) a solenoid switch whichworks to produce a magnetic attraction to attract a plunger to thrustthe pinion gear toward the ring gear and also open or close maincontacts installed in the motor circuit interlocking with movement ofthe plunger for cutting or supplying the electric power to the motor;(i) a motor on-off relay which has relay contacts disposed in the motorcircuit and opens or closes the relay contacts electrically; (g) acontroller which electrically controls an operation of the solenoidswitch and an operation of the motor on-off relay when the engine isrestarted during deceleration of the engine prior to stop of the engine;and (h) delay means for delaying a second operation time that is a timewhen the motor on-off relay is to be energized until after a firstoperation time that is a time when the solenoid switch is to beenergized when the engine is restarted. The delay means produces a timelag between the first and second operation times so as to turn on themotor on-off relay to supply the electric power to the motor after thepinion gear is moved by the solenoid switch to the ring gear and thenengages the ring gear at least partially or to a maximum movableposition where engagement of the pinion gear with the ring gear is to beestablished and then engages the ring gear, and after the main contactsare closed.

When it is requested to restart the engine during deceleration of theengine before complete stop thereof, the engine start system of thisinvention works to electrically or mechanically delay the secondoperation time when the motor on-off relay is to be energized until thefirst operation time when the solenoid switch is to be energized.Specifically, the delay means works to close the motor on-off relay tosupply the electric power to the motor after the pinion gear is moved bythe pinion solenoid actuator to the gear engageble position or themaximum movable position and then engages the ring gear, and the maincontacts have already been closed.

In other words, the motor on-off relay is not closed to keep the motordeenergized during a period of time required by the pinion gear to moveto the ring gear and then engages the ring gear. Therefore, the torque,as produced by the motor, is not transmitted to the pinion gear untilthe pinion gear engages the ring gear.

Even if the pinion gear, as moved by the solenoid switch, has failed toengage the ring gear directly, that is, the end of the pinion gear hashit the end surface of the ring gear (usually, the probability that theend of the pinion gear hits the end surface of the ring gear is higherthan that the pinion gear is moved by the solenoid switch and thenengages the ring gear directly), the pinion gear will then engage thering gear at a certain angular position because the ring gear isrotating at a lower speed. This enables the engine to be restartedquickly during deceleration of the engine before complete stop thereof.The motor is kept off until the pinion has engaged the ring gear, thusminimizing the mechanical impact or noise arising from the engagement ofthe pinion gear with the ring gear and improving the reliability inengagement with the ring gear during the deceleration of the engine anddurability of the system.

In the preferred mode of the invention, the delay means is implementedby a delay circuit connected to an excitation circuit which works toexcite the motor on-off relay and is built in the motor on-off relay.

The motor on-off relay has the relay contacts disposed upstream of themain contacts of the motor circuit. Specifically, the motor on-off relayis disposed between the solenoid switch and the battery, thuseliminating the need for altering the structure of the solenoid switch,that is, permitting the solenoid switch having a typical structure to beused.

The motor on-off relay may be installed on a housing of a starter inwhich the motor is installed. The starter is a part to be installed onthe engine. It is, thus, essential to assure the quality of the starteragainst mechanical vibrations. In order to meet such quality assurance,the motor on-off relay is secured to the starter housing which is closeto an engine mount and smallest in magnitude of the vibration.

The engine start system may be installed in a vehicle equipped with anidle stop system working to stop and restart the engine automatically.

According to the fifth aspect of the invention, there is provided anengine start system which comprises: (a) a motor which is energized bysupply of electric power from a battery through a motor circuit toproduce torque; (b) an output shaft which rotates when subjected to thetorque, as produced by the motor; (c) a pinion gear through which thetorque, as produced by the motor, is transmitted to a ring gear coupledto an engine; (d) a pinion movable body which is movable along theoutput shaft together with the pinion gear; (e) a solenoid switch whichworks to produce a magnetic attraction to attract a plunger to thrustthe pinion gear toward the ring gear and has an external terminal whichis connected to the motor circuit and through which the electric poweris supplied to the motor; (f) a motor on-off relay which has relaycontacts disposed in the motor circuit and opens or closes the relaycontacts electrically; (g) a controller which electrically controls anoperation of the solenoid switch and an operation of the motor on-offrelay when the engine is restarted during deceleration of the engineprior to stop of the engine; and (h) delay means for delaying a secondoperation time that is a time when the motor on-off relay is to beenergized until after a first operation time that is a time when thesolenoid switch is to be energized on when the engine is restarted. Thedelay means produces a time lag between the first and second operationtimes so as to turn on the motor on-off relay to supply the electricpower to the motor after the pinion gear is moved by the solenoid switchto the ring gear and then engages the ring gear at least partially or toa maximum movable position where engagement of the pinion gear with thering gear is to be established and then engages the ring gear.

When it is requested to restart the engine during deceleration of theengine before complete stop thereof, the engine start system of thisinvention works to electrically or mechanically delay the secondoperation time when the motor on-off relay is to be energized until thefirst operation time when the solenoid switch is to be energized.Specifically, the delay means works to close the motor on-off relay tosupply the electric power to the motor after the pinion gear is moved bythe solenoid switch and engages the ring gear.

In other words, the motor on-off relay is not closed to keep the motordeenergized during a period of time required by the pinion gear to moveto the ring gear and then engages the ring gear. Therefore, the torque,as produced by the motor, is not transmitted to the pinion gear untilthe pinion gear engages the ring gear.

Even if the pinion gear, as moved by the solenoid switch, has failed toengage the ring gear directly, that is, the end of the pinion gear hashit the end surface of the ring gear (usually, the probability that theend of the pinion gear hits the end surface of the ring gear is higherthan that the pinion gear is moved by the solenoid switch and thenengages the ring gear directly), the pinion gear will then engage thering gear at a certain angular position because the engine isdecelerating, so that the ring gear is rotating at a lower speed. Thisenables the engine to be restarted quickly during deceleration of theengine before complete stop thereof. The motor is kept off until thepinion has engaged the ring gear, thus minimizing the mechanical impactor noise arising from the engagement of the pinion gear with the ringgear and improving the reliability in engagement with the ring gearduring the deceleration of the engine and durability of the system.

In the preferred mode of the invention, the solenoid switch has a firstterminal bolt and a second terminal bolt. The first terminal bolt servesas the external terminal. The second terminal bolt connects with themotor through a motor lead. The first and second terminal bolts areconnected electrically through a terminal-to-terminal connector. Thiseliminates the need for main contacts installed in the solenoid switchof a typical structure. The main contacts are usually implemented by apair of fixed contacts connecting with the motor circuit through twoterminal bolts and a movable contact which is moved by movement of theplunger. The structure of the invention may thus omit the fixed contactsand the movable contact.

The solenoid switch having the typical structure may be used as it is.The two terminal bolts are connected through the connector electrically,so that the flow of electric power to the motor is not blocked orestablished by opening or closing of the main contacts. Specifically,when the motor on-off relay is turned on, the electric power is suppliedfrom the battery to the motor, while when the motor on-off relay is off,the electric power stops being supplied to the motor regardless ofopening or closing of the main contacts. The mechanical wear of the maincontacts or a failure in making connection therebetween will, therefore,not impinge upon the operation of the engine start system.

The first terminal bolt may serve as the external terminal connectingwith the motor through a motor lead. The second terminal bolt isisolated from the motor circuit without being connected to the motorcircuit. This also eliminates the need for the main contacts installedin the solenoid switch of a typical structure. Specifically, when themotor on-off relay is turned on, the electric power is supplied from thebattery to the motor, while when the motor on-off relay is off, theelectric power stops being supplied to the motor regardless of openingor closing of the main contacts. The mechanical wear of the maincontacts or a failure in making connection therebetween will, therefore,not impinge upon the operation of the engine start system.

The first terminal bolt may alternatively be isolated from the motorcircuit. The second terminal bolt may serve as the external terminalconnecting with the motor through a motor lead.

The second terminal bolt is connected to the motor, thus eliminating theneed for the main contacts installed in the solenoid switch of a typicalstructure. Specifically, when the motor on-off relay is turned on, theelectric power is supplied from the battery to the motor, while when themotor on-off relay is off, the electric power stops being supplied tothe motor regardless of opening or closing of the main contacts. Themechanical wear of the main contacts or a failure in making connectiontherebetween will, therefore, not impinge upon the operation of theengine start system.

The motor on-off relay may have the relay contacts in the motor circuitupstream of the external terminal. Specifically, the motor on-off relayis disposed between the solenoid switch and the battery, thuseliminating the need for altering the structure of the solenoid switch,that is, permitting the solenoid switch having a typical structure to beused.

The motor on-off relay may be installed on a housing of a starter inwhich the motor is installed. The starter is a part to be installed onthe engine. It is, thus, essential to assure the quality of the starteragainst mechanical vibrations. In order to meet such quality assurance,the motor on-off relay is secured to the starter housing which is closeto an engine mount and smallest in magnitude of the vibration.

The engine start system may be installed in a vehicle equipped with anidle stop system working to stop and restart the engine automatically.

According to the sixth aspect of the invention, there is provided anengine start system which comprises: (a) a motor which is energized bysupply of electric power from a battery through a motor circuit toproduce torque; (b) an output shaft which rotates when subjected to thetorque, as produced by the motor; (c) a pinion gear through which thetorque, as produced by the motor, is transmitted to a ring gear coupledto an engine; (d) a pinion movable body which is movable along theoutput shaft together with the pinion gear; (e) a solenoid switch whichworks to produce a magnetic attraction to attract a plunger to thrustthe pinion gear toward the ring gear and has a first and a secondterminal bolt connectable with the motor circuit; (f) a motor on-offrelay which has relay contacts disposed in the motor circuit and opensor closes the relay contacts electrically; (g) a controller whichelectrically controls an operation of the solenoid switch and anoperation of the motor on-off relay when the engine is restarted duringdeceleration of the engine prior to stop of the engine; and (h) delaymeans for delaying a second operation time that is a time when the motoron-off relay is to be energized until after a first operation time thatis a time when the solenoid switch is to be energized on when the engineis restarted.

The solenoid switch does not work to establish or block flow of theelectric power to the motor and has the first and second terminal boltsdisconnected from the motor circuit.

The motor on-off relay works to open or close the relay contacts toblock or establish flow of the electric power from the battery to themotor.

The delay means produces a time lag between the first and secondoperation times so as to turn on the motor on-off relay to establish theflow of the electric power to the motor after the pinion gear is movedby the solenoid switch to the ring gear and then engages the ring gearat least partially or to a maximum movable position where engagement ofthe pinion gear with the ring gear is to be established and then engagesthe ring gear.

When it is requested to restart the engine during deceleration of theengine before complete stop thereof, the engine start system of thisinvention works to electrically or mechanically delay the secondoperation time when the motor on-off relay is to be energized until thefirst operation time when the solenoid switch is to be energized.Specifically, the delay means works to close the motor on-off relay tosupply the electric power to the motor after the pinion gear is moved bythe solenoid switch and engages the ring gear.

In other words, the motor on-off relay is not closed to keep the motordeenergized during a period of time required by the pinion gear to moveto the ring gear and then engages the ring gear. Therefore, the torque,as produced by the motor, is not transmitted to the pinion gear untilthe pinion gear engages the ring gear.

Even if the pinion gear, as moved by the solenoid switch, has failed toengage the ring gear directly, that is, the end of the pinion gear hashit the end surface of the ring gear (usually, the probability that theend of the pinion gear hits the end surface of the ring gear is higherthan that the pinion gear is moved by the solenoid switch and thenengages the ring gear directly), the pinion gear will then engage thering gear at a certain angular position because the engine isdecelerating, so that the ring gear is rotating at a lower speed. Thisenables the engine to be restarted quickly during deceleration of theengine before complete stop thereof. The motor is kept off until thepinion has engaged the ring gear, thus minimizing the mechanical impactor noise arising from the engagement of the pinion gear with the ringgear and improving the reliability in engagement with the ring gearduring the deceleration of the engine and durability of the system.

Two terminal bolts installed in the solenoid switch are not used inconnecting to the motor circuit, but the solenoid switch may be used asit is. The solenoid switch does not function as an on-off switch whichestablishes or blocks the flow of electric power to the motor.Therefore, mechanical wear of main contacts (i.e., fixed contactsinstalled on the two terminal bolts and a movable contact makingconnection between the fixed contacts) or a failure in making connectiontherebetween will not impinge upon the operation of the engine startsystem.

The motor on-off relay may have the relay contacts in the motor circuitupstream of the external terminal. Specifically, the motor on-off relayis disposed between the solenoid switch and the battery, thuseliminating the need for altering the structure of the solenoid switch,that is, permitting the solenoid switch having a typical structure to beused.

The motor on-off relay may be installed on a housing of a starter inwhich the motor is installed. The starter is a part to be installed onthe engine. It is, thus, essential to assure the quality of the starteragainst mechanical vibrations. In order to meet such quality assurance,the motor on-off relay is secured to the starter housing which is closeto an engine mount and smallest in magnitude of the vibration.

The engine start system may be installed in a vehicle equipped with anidle stop system working to stop and restart the engine automatically.

According to the seventh aspect of the invention, there is provided anengine start system which comprises: (a) a motor which is energized bysupply of electric power from a battery through a motor circuit toproduce torque; (b) an output shaft which rotates when subjected to thetorque, as produced by the motor; (c) a pinion gear through which thetorque, as produced by the motor, is transmitted to a ring gear coupledto an engine; (d) a pinion movable body which is movable along theoutput shaft together with the pinion gear; (e) a solenoid switch whichworks to produce a magnetic attraction to attract a plunger to thrustthe pinion gear toward the ring gear and also open or close maincontacts installed in the motor circuit interlocking with movement ofthe plunger for cutting or supplying the electric power to the motor;(f) a normally closed type of motor on-off relay which has relaycontacts disposed in the motor circuit, when deenergized, the motoron-off relay keeping the relay contacts closed; (g) a starter relaywhich is disposed in an excitation circuit working to supply anexcitation current to the solenoid switch from the battery; (h) a motoron-off sub-relay which is disposed in an excitation circuit working tosupply an excitation current to the motor on-off relay from the battery;(i) a controller which electrically controls an operation of thesolenoid switch through the starter relay and an operation of the motoron-off relay through the motor on-off sub-relay when the engine isrestarted during deceleration of the engine prior to stop of the engine;and (j) delay means for delaying a second operation time that is a timewhen the motor on-off relay is to be energized until after a firstoperation time that is a time when the solenoid switch is to beenergized on when the engine is restarted. The delay means produces atime lag between the first and second operation times so as to turn onthe motor on-off relay to supply the electric power to the motor afterthe pinion gear is moved by the solenoid switch to the ring gear andthen engages the ring gear at least partially or to a maximum movableposition where engagement of the pinion gear with the ring gear is to beestablished and then engages the ring gear, and after the main contactsare closed.

The controller energizes the motor on-off sub-relay to open the motoron-off relay before the main contacts are closed by the solenoid switchand then closes the motor on-off relay following the first operationtime.

When it is requested to restart the engine, the engine start system ofthis invention works to electrically or mechanically delay the secondoperation time when the motor on-off relay is to be energized until thefirst operation time when the solenoid switch is to be energized.Specifically, the delay means works to close the motor on-off relay tosupply the electric power to the motor after the pinion gear is moved bythe solenoid switch and engages the ring gear.

The controller energizes the motor on-off sub-relay to turn off themotor on-off relay before the main contacts are closed by the solenoidswitch and then turn on the motor on-off relay following the firstoperation time.

When it is requested to restart the engine during deceleration of theengine prior to stop thereof, the engine start system electrically ormechanically delays the second operation time when the motor on-offrelay is to be energized until after the first operation time when thesolenoid switch is to be energized. Specifically, the delay means worksto close the motor on-off relay to supply the electric power to themotor after the pinion gear is moved by the solenoid switch and engagesthe ring gear at least partially.

The motor on-off relay is of a normally closed type. Therefore, themotor on-off sub-relay is energized to turn off the motor on-off relaybefore the solenoid switch closes the main contacts, after which themotor on-off relay is turned on after the first operation time has beenreached.

Therefore, the motor on-off relay is not closed to keep the motordeenergized during a period of time required by the pinion gear to moveto the ring gear and then engages the ring gear. Therefore, the torque,as produced by the motor, is not transmitted to the pinion gear untilthe pinion gear engages the ring gear.

The use of the normally closed type of the motor on-off relay permitsthe engine to be started by, for example, a manual key operation made bya vehicle operator if the controller has failed in operation.Specifically, the solenoid switch is activated in response to a normalinput which is produced by manual turning on of an ignition switch toexcite the starter relay independently of the controller.

Even if the pinion gear, as moved by the solenoid switch, has failed toengage the ring gear directly, that is, the end of the pinion gear hashit the end surface of the ring gear (usually, the probability that theend of the pinion gear hits the end surface of the ring gear is higherthan that the pinion gear is moved by the solenoid switch and thenengages the ring gear directly), the pinion gear will then engage thering gear at a certain angular position because the engine isdecelerating, so that the ring gear is rotating at a lower speed. Thisenables the engine to be restarted quickly during deceleration of theengine before complete stop thereof. The motor is kept off until thepinion has engaged the ring gear, thus minimizing the mechanical impactor noise arising from the engagement of the pinion gear with the ringgear and improving the reliability in engagement with the ring gearduring the deceleration of the engine and durability of the system.

The motor on-off relay may have the relay contacts in the motor circuitupstream of the external terminal. Specifically, the motor on-off relayis disposed between the solenoid switch and the battery, thuseliminating the need for altering the structure of the solenoid switch,that is, permitting the solenoid switch having a typical structure to beused.

The motor on-off relay may be installed on a housing of a starter inwhich the motor is installed. The starter is a part to be installed onthe engine. It is, thus, essential to assure the quality of the starteragainst mechanical vibrations. In order to meet such quality assurance,the motor on-off relay is secured to the starter housing which is closeto an engine mount and smallest in magnitude of the vibration.

The engine start system may be installed in a vehicle equipped with anidle stop system working to stop and restart the engine automatically.

According to the eighth aspect of the invention, there is provided anengine start system which comprises: (a) a motor which is energized bysupply of electric power from a battery through a motor circuit toproduce torque; (b) an output shaft which rotates when subjected to thetorque, as produced by the motor; (c) a pinion gear through which thetorque, as produced by the motor, is transmitted to a ring gear coupledto an engine; (d) a pinion movable body which is movable along theoutput shaft together with the pinion gear; (e) a solenoid switch whichworks to produce a magnetic attraction to attract a plunger to thrustthe pinion gear toward the ring gear and also open or close maincontacts installed in the motor circuit interlocking with movement ofthe plunger for cutting or supplying the electric power to the motor;(f) a motor on-off relay which has relay contacts disposed in the motorcircuit and opens or closes the relay contacts electrically; and (g) acontroller which electrically controls an operation of the solenoidswitch and an operation of the motor on-off relay. During decelerationof the engine prior to stop of the engine, the controller energizes thesolenoid switch to move the pinion gear and delays the operation of themotor on-off relay until after the pinion bear engages the ring gear atleast partially or the pinion is moved to a maximum movable positionwherein engagement of the pinion gear with the ring gear is to beestablished and then engages the ring gear, and the main contacts areclosed, after which an engine restart request signal is inputted to thecontroller.

When the engine is decelerating prior to stop of the engine, the enginestart system of this invention thrusts and brings the pinion gear intoengagement with the ring gear of the engine and then energizes the motoron-off relay to activate the motor to crank the engine in response tothe engine restart request signal inputted to the controller, that is,when engine restart conditions are met. In other words, the controllerdoes not turn on the solenoid switch to bring the pinion gear intoengagement with the ring gear in response to the engine restart requestsignal, but achieves the engagement of the pinion gear with the ringgear while the engine is decelerating before being stopped and keepssuch engagement after the engine stops.

Afterwards, when the engine restart conditions are met, for example, thevehicle operator has released the brake pedal and shifted the selectlever of the automatic transmission to the drive, the engine restartsignal is inputted to the controller. The controller then energizes themotor on-off relay to supply the electric power from the battery to themotor to rotate the pinion gear which has already engaged the ring gear.The torque produced by the motor is, therefore, transmitted quickly tothe ring gear to crank the engine. This minimizes the mechanical impactor noise arising from the engagement of the pinion gear with the ringgear.

In the preferred mode of the invention, the motor on-off relay has therelay contacts in the motor circuit upstream of the external terminal.Specifically, the motor on-off relay is disposed between the solenoidswitch and the battery, thus eliminating the need for altering thestructure of the solenoid switch, that is, permitting the solenoidswitch having a typical structure to be used.

The motor on-off relay may be installed on a housing of a starter inwhich the motor is installed. The starter is a part to be installed onthe engine. It is, thus, essential to assure the quality of the starteragainst mechanical vibrations. In order to meet such quality assurance,the motor on-off relay is secured to the starter housing which is closeto an engine mount and smallest in magnitude of the vibration.

The engine start system may be installed in a vehicle equipped with anidle stop system working to stop and restart the engine automatically.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood more fully from the detaileddescription given hereinbelow and from the accompanying drawings of thepreferred embodiments of the invention, which, however, should not betaken to limit the invention to the specific embodiments but are for thepurpose of explanation and understanding only.

In the drawings:

FIG. 1 is a partially sectional view which shows a starter installed inan engine start system according to the first embodiment of theinvention;

FIG. 2 is a longitudinal sectional view which shows an internalstructure of a solenoid actuator and a solenoid relay installed in thestarter of FIG. 1;

FIG. 3 is a circuit diagram which shows an engine start system accordingto the first embodiment of the invention;

FIG. 4 is a graph which demonstrates a relation between the magnitude ofimpact arising from engagement of a pinion gear with a ring gear whilean engine is being reversed and a time lag elapsed from movement of apinion gear;

FIG. 5 is a circuit diagram which shows an engine start system accordingto the second embodiment of the invention;

FIG. 6 is a circuit diagram which shows an engine start system accordingto the third embodiment of the invention;

FIG. 7 is a partially sectional view which shows a starter installed inan engine start system according to the fourth embodiment of theinvention;

FIG. 8 is a circuit diagram which shows an engine start system accordingto the fifth embodiment of the invention;

FIG. 9 is a circuit diagram which shows an engine start system accordingto the sixth embodiment of the invention;

FIG. 10 is a circuit diagram which shows an engine start systemaccording to the seventh embodiment of the invention;

FIG. 11 is a circuit diagram which shows an engine start systemaccording to the eighth embodiment of the invention;

FIG. 12 is a circuit diagram which shows an engine start systemaccording to the ninth embodiment of the invention;

FIG. 13 is a circuit diagram which shows an engine start systemaccording to the tenth embodiment of the invention;

FIG. 14 is a circuit diagram which shows an engine start systemaccording to the eleventh embodiment of the invention;

FIG. 15 is a circuit diagram which shows an engine start systemaccording to the twelfth embodiment of the invention;

FIG. 16 is a circuit diagram which shows an engine start systemaccording to the thirteenth embodiment of the invention; and

FIG. 17 is a circuit diagram which shows an engine start systemaccording to the fourteenth embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings, wherein like reference numbers refer to likeparts in several views, particularly to FIG. 3, there is shown an enginestart system according to the first embodiment of the invention whichmay be used with an idle stop system to stop an automotive engineautomatically when a vehicle has stopped, for example, at anintersection or due to a traffic jam and then restart the engine when avehicle driver performs a given starting operation (e.g., release of thedriver's foot from the brake pedal). The engine start system includes anengine starter 1, as illustrated in FIG. 1, and an electronic controlunit (ECU) 2 which controls an operation of the starter 1.

The starter 1 consists essentially of a starter motor 3, an output shaft4 through which torque, as produced by the motor 3 is transmitted, aone-way clutch 5 fit on the outer periphery of the output shaft 4through a helical spline, a pinion gear 6 movable on the outer peripheryof the output shaft 4 in an axial direction thereof (i.e., a lateraldirection in FIG. 1) along with the one-way clutch 5, a solenoidactuator 8 working as a pinion actuator to push the clutch 5 and thepinion gear 6 away from the motor 3 through the shift lever 7, and asolenoid motor on-off switch 10 working to open or close main contacts,as will be described later, installed in a motor circuit which isconfigured to supply the electric power or current to the motor 3. Theone-way clutch 5 is of a typical structure made of an outer, an inner,rollers, and springs.

The pinion gear 6 is formed integrally with the inner of the one-wayclutch 5. The pinion gear 6 and the one-way clutch 5 work as a pinionmovable body. A speed reducer (not shown) may be disposed between themotor 3 and the output shaft 4 to reduce the speed of the motor 3 andtransmit it to the output shaft 4. The speed reducer may be implementedby an epicycle reduction gear.

The structure of the solenoid actuator 8 and the motor on-off switch 10will be described below with reference to FIGS. 2 and 3.

The motor 3, the output shaft 4, the clutch 5, the pinion gear 6, theshift lever 7, the starter housing 11, and the speed reducer havetypical structures known in the art which are not essential parts of theinvention, and explanation thereof in detail will be omitted here.

The solenoid actuator 8 and the motor on-off switch 10 are aligned ordisposed in series in an axial direction thereof as a unit and, as canbe seen from FIG. 1, secured to the starter housing 11 in parallel tothe starter motor 3.

The solenoid actuator 8, as illustrated in FIG. 2, consists of asolenoid case 12, a solenoid coil 14 wound around a resinous bobbin 13within the solenoid case 12, a stationary magnetic core 15 to bemagnetized by energization of the solenoid coil 14, a plunger 16disposed to be movable in the solenoid coil 14 in an axial directionthereof, and a joint 17 through which the movement of the plunger 16 istransmitted to the shift lever 7.

The solenoid case 12 is made of a hollow cylinder with a bottom 12 aclosing one of opposed ends thereof. The bottom 12 a has formed in theradial center thereof a circular hole whose diameter is identical withan inner diameter of the bobbin 13. A hollow cylindrical sleeve 18 isinserted into the inner periphery of the bobbin 13 through the circularhole of the bottom 12 a to guide the movement of the plunger 16.

The solenoid coil 14 is made up of a pull-in coil 14 a and a hold-oncoil 14 b which are wound around the bobbin 13 in the form of twolayers. The pull-in coil 14 a and the hold-on coil 14 b are joined atends thereof to a first external terminal 19, as illustrated in FIG. 3.The first external terminal 19 is connected to the battery 9 through astarter relay 20. The pull-in coil 14 a is also connected at the otherend thereof to a second external terminal 21, as illustrated in FIG. 3.The second external terminal 21 is coupled to an M-terminal bolt 32, aswill be described later in detail, through a metal connector (notshown). The hold-on coil 14 b is also welded at the other end thereof tothe surface of the magnetic core 15 so that it is electrically connectedto ground.

The starter relay 20 is turned on or off by the ECU 2. When turned on,the starter relay 20 supplies the electric power from the battery 9 tothe solenoid coil 14.

The stationary magnetic core 15 is made by an assembly of an annularplate 15 a and a core 15 b swaged so that it is fit in the innerperiphery of the annular plate 15. The plate 15 a has an outerperipheral edge facing the solenoid coil 14 which is placed in abutmentwith an inner shoulder formed in the inner wall of the solenoid case 12so that it is held from moving to the solenoid coil 14.

The plunger 16 is disposed to be movable along the inner periphery ofthe sleeve 18 in the axial direction of the sleeve 18. A return spring22 is interposed between the core 15 and the plunger 16 to urge theplunger 16 away from the core 15 (i.e., the left direction, as viewed inFIG. 2). The plunger 16 is made of a hollow cylinder with a circularcenter hole extending in the axial direction of the plunger 16. Thecenter hole opens at one of ends of the plunger 16 and is closed by theother end of the plunger 16.

The joint 17 is inserted into the center hole of the plunger 16 alongwith a drive spring 23. The joint 17 is made of a bar and has formed inan end thereof a groove 17 a with which an end of the shift lever 7engages. The joint 17 also has a flange 17 b formed on the other endthereof. The flange 17 b has an outer diameter so as to have an outerperiphery thereof placed in slidable contact with the inner wall of thecenter hole of the plunger 16. The flange 17 b is urged by the drivespring 23 into constant abutment with the bottom of the center hole ofthe plunger 16.

The drive spring 23 is disposed around the outer periphery of the joint17 and held at an end thereof by a spring support 24 which is swaged orfit on an inner wall of an opening of the plunger 16 and at the otherend thereof by the flange 17 b of the joint 17. The drive spring 23continues to be compressed until the end of the pinion gear 6 pushed bythe end of the shift lever 7 moved away from the starter motor 3 by theplunger 16 hits the end of the ring gear 25 joined to the crankshaft ofthe engine, after which the plunger 16 starts to be attracted by thecore 15 b, thereby building up or accumulating reactive force thereinwhich serves to bring the pinion gear 6 into meshing engagement with thering gear 25.

The motor on-off switch 10 has the magnetic core 15 shared with thesolenoid actuator 8 and is formed integrally with the solenoid actuator8. The motor on-off switch 10 also includes a hollow cylindrical relaycase 26, a relay coil 28, a movable core 29, a contact cover 30,terminal bolts 31 and 32, a pair of fixed contacts 33, and a movablecontact 34. The relay case 26 is formed integrally with the solenoidcase 112 and extends from an open end of the solenoid case 112 inalignment therewith. The relay coil 28 is wound around a resinous bobbin27. The movable core 29 is disposed inside the relay coil 28 to bemovable in an axial direction of the relay coil 28. The contact cover 30is made of resin and fit in an open end of the relay case 26. Theterminal bolts 31 and 23 are installed in the contact cover 30. Thefixed contacts 33 are connected electrically to the motor circuit (i.e.,circuit components of the motor on-off switch 10) through the terminalbolts 31 and 32. The movable contact 34 is disposed inside the contactcover 30 to be movable to establish or block an electric connectionbetween the fixed contacts 33.

The relay coil 28 is located inside the inner periphery of the relaycase 26 closer to the end of the relay case 26 than the plate 15 a ofthe magnetic core 15. Specifically, the solenoid coil 14 is locatedacross the plate 15 a from the relay coil 28. The relay coil 28 is, asillustrated in FIG. 3, joined at an end thereof to a third terminal 35and at the other end thereof to the surface of the magnetic core 15 sothat it is electrically connected to ground. The third terminal 35 isconnected to the ECU 2 through an electric line.

A spacer 36 is disposed on the outer periphery of the relay coil 28. Amagnetic plate 37 is disposed adjacent one of the end surfaces of therelay coil 28 which is located farther away from the plate 15 a.

The spacer 36 is made of a hollow cylinder and fit in the innercircumference of the relay case 26 without any air gap. The spacer 36 isplaced in abutment of an end thereof with the end surface of the plate15 a so that it is held from moving toward the plate 15 a.

The magnetic plate 37 is insert-molded in resin material by which thebobbin 27 is formed. The magnetic plate 37 extends perpendicular to theaxis of the spacer 36 and is placed with an outer peripheral edgeextending outside the resin material in contact abutment with the end ofthe spacer 36 so that it is held from moving toward the spacer 36. Themagnetic plate 37 has formed therein a circular center hole whose innerdiameter is substantially identical with that of the bobbin 27 so thatthe movable core 29 may move through the center hole.

The movable core 29 is disposed to be movable along the innerperipheries of the magnetic plate 37 and the bobbin 27 in the axialdirection thereof. A return spring 38 is disposed between the core 15 band the movable core 29 to urge the movable core 29 elastically awayfrom the core 15 b (i.e., the right direction, as viewed in FIG. 2).

The contact cover 30 is of a cylindrical shape and includes a hollowcylindrical leg 30 a which is disposed in the opening of the relay case26 with an end thereof in contact abutment with the surface of themagnetic plate 37. The entire or partial circumference of the open endof the relay case 26 is crimped to retain the leg 30 a of the contactcover 30 firmly.

The terminal bolts 31 and 32 serve as a B-terminal bolt to which abattery cable 39 is, as illustrated in FIG. 3, is joined and anM-terminal bolt to which a motor lead 40 is, as illustrated in FIGS. 1and 3, joined. The terminal bolts 31 and 32 are installed in the contactcover 30 through washers 41 and 42.

The fixed contacts 33 are separate from the terminal bolts 131 and 132,but may alternatively be formed integrally therewith, respectively. Thefixed contacts 33 are electrically connected to the terminal bolts 31and 32 within the contact cover 30, respectively.

The movable contact 34 is disposed farther away from the movable core 29than the fixed contacts 33. The movable contact 34 is urged by a contactpressure spring 44 into constant abutment with an end surface of aresinous rod 43 secured in the movable core 29. An initial springpressure, as produced by the contact pressure spring 44, is set smallerthan that, as produced by the return spring 38, thus causing the movablecontact 34 to be placed, as can be seen in FIG. 9, in constant abutmentwith an inner seat 30 b of the contact cover 30 while compressing thecontact pressure spring 44 when the relay coil 28 is deenergized.

The main contacts are the fixed contacts 33 and the movable contact 34.The closing of the main contacts is achieved by urging the movablecontact 34 through the contact pressure spring 44 into abutment with thefixed contacts 33 to make an electric connection between the fixedcontacts 33. The opening of the main contacts is achieved by moving themovable contact 34 away from the fixed contacts 33 to break the electricconnection between the fixed contacts 33.

The idle stop control mode to be performed by the ECU 2 will bedescribed below.

When the ECU 2 monitors, for example, signals indicating the speed ofthe engine, the position of the selector lever of the automatictransmission, and an on/off state of the brake switch, as inputted froman engine ECU (not shown), and determines based on the signals thatautomatic engine stop conditions, for example, where the vehicle speedis zero (0), and the brake pedal has been depressed have been met, theECU 2 outputs an engine stop request signal to the engine ECU.

Afterwards, when engine restart conditions, for example, where the brakepedal has been released, and the select lever of the automatictransmission has been shifted to a drive (D) range are met, the ECU 20decides that a request to restart the engine is made after the idle stopcontrol mode has been executed, and outputs an engine restarting signalto the engine ECU and also controls the operation of the starter 1 torestart the engine.

Specifically, the ECU 2 energizes the solenoid coil 14 to turn on thesolenoid actuator 8, and then energizes the relay coil 28 to operate themotor on-off switch 10. The first operation time at which the ECU 2should energize the solenoid coil 14 is delayed a preselected period oftime until after the second operation time at which the ECU 2 shouldenergize the relay coil 28. The time lag between the first and secondoperation times is changed between when the engine restart conditionsare met after the automatic engine stop conditions are met to cut thesupply of fuel and intake air to the engine, and then the engine stopscompletely and when the engine restart conditions are met before theengine stops completely.

For example, when the engine restart conditions are met after the enginestops completely, the time lag is set to 15 ms. to 20 ms. (in thisembodiment, 20 ms.). When the engine restart conditions are met beforethe engine stops completely, that is, while the ring gear 25 isrotating, the time lag is set to 30 ms. or more, preferably 40 ms. ormore.

When a time interval between when the pinion gear 6 has been thrust bythe solenoid actuator 8 along with the clutch 5 toward the ring gear 25and when the main contacts are closed by the motor on-off switch 10,that is, the above time lag is set to 20 ms., the ECU 2 will close themain contacts to energize the starter motor 3 substantially concurrentlywith when the end of the pinion gear 6 hits the end surface of the ringgear 25. When the time lag is set to 30 ms. or more, the ECU 2 will keepthe main contacts opened until the pinion gear 6 advances to anengageble position where the pinion gear 6 is engable with the ring gear25 and then engages the ring gear 25 and then close them after thepinion gear 6 has engaged the ring gear 25. The phrase “until the piniongear 6 advances to the engageble position and then engages with the ringgear 25” does not necessarily mean “until the ring gear 13 has engagedthe entire width of the ring gear 25 completely”, but it contains themeaning of “until the pinion gear 6 at least partially engages the widthof the ring gear 25.

The operation of the starter 1 in the first embodiment will be describedbelow.

When Normal Engine Start is Made (Vehicle Operator Turns on IgnitionSwitch to Start Completely Stopped Engine)

In response to an on-signal produced upon turning on of the ignitionswitch, the ECU 2 turns on the starter relay 20, so that the electricpower is supplied from the battery 9 to the solenoid coil 14 tomagnetize the core 15 b, thereby attracting the plunger 16. This causesthe pinion gear 6 to be thrust by the shift lever 7 away from thestarter motor 3 along with the one-way clutch 5. When hitting the endsurface of the ring gear 25, the pinion gear 6 stops.

When the time lag (e.g., 20 ms.) has elapsed following the energizationof the solenoid coil 14, the ECU 2 energizes the relay coil 28 toattract the movable core 29 to the core 15 b of the magnetic core 15,thereby causing the movable contact 34 to be urged by the contactpressure spring 44 into abutment with the fixed contacts 33 to make theelectric connection therebetween (i.e., close the main contacts), sothat the electric power is supplied form the battery 9 to the startermotor 3. This causes the armature 3 a, as illustrated in FIG. 3, toproduce torque which is, in turn, transmitted to the pinion gear 6through the output shaft 4 and the one-way clutch 5. When the piniongear 6 rotates until an engageble position where it is engageble withthe ring gear 25, it will cause the pinion 6 to be brought by thereactive pressure, as accumulated in the drive spring 23, intoengagement with the ring gear 25, so that the torque is transmitted fromthe pinion gear 6 to the ring gear 25 to crank the engine.

When Engine Restart is Made after Idling of Engine is Required to beStopped

When the engine restart conditions are met after the rotation of theengine is stopped completely, the ECU 2 turns on the starter relay 20 toenergize the solenoid coil 14. After an elapse of 20 ms. from the firstoperation time, the ECU 2 energizes the relay coil 28, thereby thrustingthe pinion gear 6 away from the starter motor 3 through the shift lever7 along with the one-way clutch 5. The ECU 2 also energizes the startermotor 3 substantially at the same time as a hit of the end of the piniongear 6 with the end surface of the ring gear 25. This causes the piniongear 6 to be rotated by the torque output from the starter motor 3 to anangular position (i.e., the engageble position) and then engage the ringgear 25 to crank the engine.

When the engine restart conditions are met before the rotation of theengine is stopped completely, the ECU 2 turns on the relay coil 28 afteran elapse of the time lag (e.g., 40 ms.) since the first operation time.At the time when the end of the pinion gear 6 hits the end surface ofthe ring gear 25, the main contacts are not yet closed, so that thestarter motor 3 is still in the off-state, and the pinion gear 6 is notrotated. However, the pinion gear 6 has been thrust to the ring gear 25while the ring gear 25 is rotating, thus causing the engagement of thepinion gear 6 with the ring gear 25 to be achieved when the pinion gear6 has hit the ring gear 25 and then rotated toward the engagebleposition at which the pinion gear 6 is to engage the ring gear 25.Afterwards, the ECU 2 turns on the motor on-off switch 10 to close themain contacts, so that the starter motor 3 is actuated to output thetorque to the pinion gear 6 to crank the engine through the ring gear25.

The engine start system of this embodiment has the following advantages.

When the engine restart conditions are met after the idle stop requestis made to cut the supply of fuel and intake air to the engine, but theengine is still decelerating (e.g., the engine is swinging oroscillating in rotation, that is, the engine is rotating in the normaland the reverse direction cyclically), the engine start system actuatesthe starter 1 to restart the engine. The ECU 2 produces the time lagbetween the first operation time and the second operation time so as tokeep the start motor 3 turned off until the pinion gear 6 meshes withthe ring gear 25. For example, the second operation time is delayed 30ms. or more (preferably 40 ms. or more) until after the first operationtime, thereby keeping the starter motor 3 in the off-state until thepinion gear 6 meshes with the ring gear 25, thereby minimizingmechanical impact or noise arising from the engagement of the piniongear 6 with the ring gear 25 to ensure the reliability in operation andthe service life of the starter 1.

We measured the relation between the magnitude of mechanical impactarising from the engagement of the pinion gear 6 with the ring gear 25and the time lag set between the first and second operation times.Results of such measurement are shown in a graph of FIG. 4. The verticalaxis indicates the magnitude of impact appearing when the pinion gear 6meshes with the ring gear 25 while the ring gear 25 is rotating at aconstant speed in a reverse direction. The horizontal axis indicates thetime interval between when the pinion gear 6 is pushed by the shiftlever 7 and when the starter motor 3 is energized, that is, the time lagbetween the first and second operation times.

“Standard starter” in the graph represents typical pinion-thrustingstarters designed to thrust the pinion gear 6 through a single solenoidswitch to open or close the main contacts. The range, as delimited by anarrow, indicates a time interval of about 15 ms. to 25 ms. between whenthe pinion gear 6 is thrust and when the starter motor 3 is energized,in other words, the time lag between the energization of the solenoidswitch and closing of the maim contacts. In the case where the time lagis 15 ms. to 25 ms., the standard starter energizes the starter motor 3substantially at the same time as the pinion gear 6 hits the ring gear25, which may cause the pinion gear 6 rotating in the normal directionto mesh with the ring gear 25 rotating in the reverse direction, thusproducing a great impact.

When the time lag between the thrusting of the pinion gear 6 and theenergization of the starter motor 3 is 30 ms. or more, it will cause thestarter motor 3 to be energized when the pinion gear 6 is placed in meshwith the ring gear 25. In this case, the torque, as produced by thestarter motor 3, is not exerted on the pinion gear 6 at the time whenthe pinion gear 6 engages the ring gear 25, thus resulting in a decreasein mechanical impact produced upon the engagement of the pinion gear 6with the ring gear 25. Particularly, when the time lag is 40 ms. ormore, the magnitude of the impact has found to be lower than that whenthe ring gear 25 is stopped, and the engine starts.

As apparent from the above discussion, the use of the time lag of 30 ms.or more (preferably 40 ms. or more) between the first and secondoperation times will result in a decrease in level of impact airing fromthe engagement of the pinion gear 6 with the ring gear 25. This avoidsthe damage to the pinion gear 6 and the ring gear 25 even when thestarter 1 is actuated during the deceleration of the engine (e.g., theswinging in rotation of the engine) before the engine stops completely.Therefore, when it is required to restart the engine while the engine isstill decelerating immediately after the vehicle stops, the engine startsystem works to restart the engine quickly without causing trouble tofollowing vehicles, thus eliminating the mental load on the vehicleoperator.

The engine start system of this embodiment is, as described above,designed to use the time lag between the first and second operationtimes which is different between a first restart mode in which theengine is restarted after the rotation of the engine stops completelyand a second restart mode in which the engine is restarted before therotation of the engine stops completely. It is, therefore, possible toset the time lags to values suitable for the first and second restartmodes independently. The time lags in the first and second restart modesmay alternatively be selected to have the same value (e.g., 30 ms. ormore, preferably 40 ms. or more).

The time lag may also be determined so as not to energize the relay coil28 of the motor on-off switch 10 until, after the solenoid coil 14 ofthe solenoid actuator 8 is energized, the pinion gear 6 advances from arest position, as illustrated in FIG. 1, at which the starter motor 3 isat rest to a maximum movable position and then engages the ring gear 25,in other words, so as to energize the relay coil 28 after the piniongear 6 is thrust to the maximum movable position and then engages thering gear 25. The maximum movable position is the position where one ofthe opposed ends of the pinion gear 6 which is farther from the one-wayclutch 5 abuts or hits the end surface of the pinion stopper 45, asillustrated in FIG. 1, which is fit on the outer periphery of the outputshaft 4, in other words, the position where the pinion gear 6 isengageble with the ring gear 25, that is, the engagement of the piniongear 6 with the ring gear 25 is to be established. When the pinion gear6 has been placed in abutment with the pinion stopper 45, it means thefact that the pinion gear 6 has engaged the entire width of the ringgear 25 completely, in other words, the complete engagement of thepinion gear 6 with the ring gear 25 is achieved.

The solenoid actuator 8 and the motor on-off switch 10 are, as describedabove, arrayed in series in the axial direction thereof (i.e., the motor3) as a unit, thereby resulting in a decrease in area of the starter 1projected in the axial direction as compared with when they are arrangedradially of the motor 3. In other words, it results in a decrease insize of the motor 3 in radial directions thereof. This permits thestarter 1 to be installed in substantially the same sized space as whena single solenoid switch (e.g., the solenoid switch 50 in FIG. 7) isused to thrust the pinion gear 6 and open or close the main contacts ofthe motor circuit.

The solenoid actuator 8 and the motor on-off switch 10 share themagnetic core 15 with each other which is disposed between the solenoidcoil 14 and the relay coil 28. The solenoid case 12 and the relay case26 are formed integrally and arrayed in alignment with the axialdirection of the solenoid actuator 8 (i.e., the motor 3). This resultsin decreases in part and assembling process of the starter 1. Theintegral formation of the solenoid case 12 and the relay case 26enhances the resistance to external mechanical vibrations.

FIG. 5 illustrates an engine start system according to the secondembodiment of the invention.

The engine start system of the first embodiment is designed to controlthe first operation time and the second operation time through the ECU2, while the engine start system of this embodiment is designed tocontrol the time lag between the first and second operation times usinga delay circuit 46.

The delay circuit 46 is, as can be seen in FIG. 5, connected between anelectric line extending from the starter relay 20 to the solenoid coil14 and the relay coil 28. When the ECU 2 turns on the starter relay 20,the delay circuit 46 delays the energization of the relay coil 28 (i.e.,the second operation time) for a given period of time (e.g., 40 ms.)until after the energization of the solenoid coil 14 (i.e., the firstoperation time).

Specifically, the delay circuit 46 works to keep the start motor 3 inthe off-state until the pinion gear 6 engages the ring gear 25, thusminimizing the mechanical impact arising from the engagement of thepinion gear 6 with the ring gear 25, which ensures the reliability inoperation and durability of the starter 1.

The use of the delay circuit 46 to set the lag time between the firstand second operation times permits the ECU 2 only to control an on-offoperation of the starter relay 20 when it is required to actuate thestarter 1, thus eliminating the need for increasing ports of the ECU 2and permitting the ECU 2 to have a typical structure.

The third embodiment of the invention will be described below withreference to FIG. 6 which is a modification of the second embodiment.

Specifically, the engine start system of this embodiment is differentfrom that of the second embodiment in structure of the delay circuit 46which sets the time lag between the first and second operation times.

A single electric wire 47 extends from an output port of the ECU 2 andconnects with two branch lines: a first relay wire 47 a and a secondrelay wire 47 b. The first relay wire 47 a leads to a first relay 48.The second relay wire 47 b leads to a second relay 49 through the delaycircuit 46.

The first relay 48 is identical in operation and structure with thestarter relay 20 of the first embodiment, as illustrated in FIG. 3, anddisposed as a component part in an excitation circuit which supplies anexcitation current from the battery 9 to the solenoid actuator 8. Thesecond relay 49 is disposed as a component part in an excitation circuit(not shown in the first embodiment) which supplies an excitation currentfrom the battery 9 to the motor on-off switch 10.

The delay circuit 46 is connected to the second relay wire 47 b and,when the ECU 2 outputs the excitation current (i.e., an on-signal) tothe starter relay 20, functions to delay the energization of the secondrelay 49 (i.e., the second operation time) for a given period of time(e.g., 40 ms.) until after the energization of the first relay 48 (i.e.,the first operation time).

The structure of this embodiment eliminates the need for discreteconnections of the first relay wire 47 a and the second relay wire 47 bto different output ports of the ECU 20. In other words, the first andsecond relay wires 47 a and 47 b are joined through the single electricline 47 to the output port of the ECU 20.

Additionally, there is no need to supply as great a current as that tothe solenoid actuator 8 to the first and second relay wires 47 a and 47b. The amount of current required only to excite the first and secondrelays 48 and 49 flows through the first and second relay wires 47 a and47 b, thus permitting the first and second relay wires 47 a and 48 b tobe made by a low-power thin wire, which leads to a decrease inmanufacturing cost of the system.

The fourth embodiment of the invention will be described below withreference to FIG. 7.

The pinion-push starter 1 of this embodiment is designed to push thepinion gear 6 and close the main contacts using a single solenoid switch50.

The solenoid switch 50 is disposed in the starter 1 and includes aswitch coil 51 and a plunger 52. When energized, the switch coil 51functions as an electromagnet to produce magnetic attraction to attractthe plunger 52. The plunger 52 is disposed to be slidable within thesolenoid switch 50 in an axial direction thereof to thrust the pinion 6toward the ring gear 25 and also close the main contacts simultaneouslyor interlocking with the movement of the plunger 52. A stroke of theplunger 52, that is, a distance the plunger 52 is to be moved is sodetermined that the main contacts are closed substantially at the sametime as the end of the pinion gear 6 hits the end surface of the ringgear 25.

In this embodiment, the stroke of the plunger 52 is lengthened more thanthe typical one so that the second operation time when the main contactsare closed may be delayed until after the first operation time when thepinion gear 6 hits the ring gear 25. Such a time lag is, like in thefirst embodiment, 30 ms. or more, preferably 40 ms. or more.

Specifically, when it is required to restart the engine after the idlestop request is made, the starter 1 of this embodiment designed tothrust the pinion gear 6 and also close the main contacts using thesolenoid switch 50 works to actuate the starter motor 3 after the piniongear 6 meshes with the ring gear 25. Therefore, even when it isrequested to restart the engine while the engine is still decelerating,the torque, as produced by the starter motor 3, is not exerted on thepinion gear 6 at the time when the pinion gear 6 engages the ring gear25, thus resulting in a decrease in mechanical impact or noise producedupon the engagement of the pinion gear 6 with the ring gear 25.

FIG. 8 illustrates an engine start system of the fifth embodiment whichis a modification of the fourth embodiment. Specifically, the enginestart system includes the pinion-push starter 1 equipped with thesolenoid switch 50, as illustrated in FIG. 7, and a motor on-off relay53.

The solenoid switch 50 of this embodiment is, unlike the fourthembodiment, designed to have a stroke of the plunger 52 which is soselected that the second operation time when the main contacts are to beclosed and the first operation time when the pinion gear 6 is to hit thering gear 25 will coincide with each other.

The motor on-off relay 53, as illustrated in FIG. 8, has relay contactswhich are disposed in the motor circuit and located upstream of the maincontacts (i.e., the contacts 33 and 34) and works to open or close therelay contacts electrically. Specifically, the motor on-off relay 53 hasa pair of fixed contacts 53 a disposed in a cable line connectingbetween a plus terminal of the battery 9 and the B-terminal bolt 31, asillustrated in FIG. 7, of the solenoid switch 50. The motor on-off relay53 also has a movable contact 53 c and a solenoid 53 b. When energized,the solenoid 53 b pushes the movable contact 53 c to establish electricconnection between the fixed contacts 53 a.

An excitation circuit which works to supply an excitation current to themotor on-off relay 53 from the battery 9 has installed therein a motoron-off sub-relay 54 which are opened or closed by the ECU 2 along withthe starter relay 20. The starter relay 20 is, like in the firstembodiment, disposed in an excitation circuit which supplies anexcitation current to the solenoid switch 50.

The ECU 2 has a delay function which is to be performed when it isrequested to restart the engine during the deceleration of the engine todelay the energization of the motor on-off sub-relay 54 to turn on themotor on-off relay 53 to energize the solenoid 53 b (i.e., the secondoperation time) for a given period of time of 30 ms. or more,preferably, 40 ms, or more until after the energization of the starterrelay 20 to active the solenoid switch 50 to energize the switch coil 51(i.e., the first operation time).

The operation of the engine start system will be described below.

When the engine restart conditions are met before the engine stopsrotating completely, the ECU 2 energizes the starter relay 20. After anelapse of 30 ms, preferably 40 ms. or more, the ECU 2 energizes themotor on-off sub-relay 54.

When the starter relay 20 is turned on, the current is supplied from thebattery 9 to the switch coil 51 of the solenoid switch 50, so that theelectromagnet is produced. The electromagnet attracts the plunger 52(i.e., the right in FIG. 7), thereby thrusting the pinion movable bodythrough the shift lever 7 until the end surface of the pinion gear 6hits the end surface of the ring gear 25.

The movement of the plunger 52 causes the movable contact 34, asillustrated in FIG. 7, to be brought into abutment with the fixedcontacts 33 (only one disposed on the B-terminal bolt 31 is illustratedin FIG. 7), thereby closing the main contacts. At the time when the maincontacts are closed, the motor on-off relay 53 is not yet turned on, sothat no current is supplied from the battery 9 to the motor 3.

At the time when the end surface of the pinion 6 has hit the end surfaceof the ring gear 25, and then the ring gear 25 has reached the positionwhere it is engageble with the pinion gear 6, the pinion gear 6 isbrought into engagement with the ring gear 6. Afterwards, the motoron-off relay 53 is turned on to supply the current from the battery 9 tothe motor 3. This restarts the engine before the engine stops rotatingcompletely, in other words, during the deceleration of the engine. Themotor 3 is kept in the off-state until the pinion 6 meshes with the ringgear 25, thus minimizing the mechanical impact or noise arising from theengagement of the pinion gear 6 with the ring gear 25 to ensure thereliability in operation and the service life of the starter 1.

The ECU 2, as described above, sets the time lag between the first andsecond operation times to 30 ms. or more (preferably 40 ms. or more),but may alternatively select it so that after the starter relay 20 isturned on to thrust the pinion movable body through the solenoid switch50, the pinion gear 6 moves from the rest position to the maximummovable position where the engagement of the pinion gear 6 with the ringgear 25 is to be achieved, and then engages the pinion gear 6, the motoron-off relay 53 is turned on to energize the motor 3.

The maximum movable position, as referred to above, is the positionwhere one of the opposed ends of the pinion gear 6 which is farther fromthe one-way clutch 5 abuts or hits the end surface of the pinion stopper45, as illustrated in FIG. 7, which is fit on the outer periphery of theoutput shaft 4. When the pinion gear 6 has been placed in abutment withthe pinion stopper 45, it means the fact that the pinion gear 6 hasengaged the entire width of the ring gear 25 completely, in other words,the complete engagement of the pinion gear 6 with the ring gear 25 isachieved.

The sixth to ninth embodiments of the invention will be described below.

An engine start system of each of the sixth to ninth embodiments isidentical with that of the fifth embodiment in structure of the starter1 with the solenoid switch 50 and the motor on-off relay 53.

The B-terminal bolt 31 of the solenoid switch 50 is, as can be seen inFIG. 9, connected electrically to the M-terminal bolt 32 through aterminal-to-terminal connector 55. The flow of current from the battery9 to the motor 3 is, therefore, established or blocked only by closingor opening the motor on-off relay 53 regardless of opening or closing ofthe main contacts by the solenoid switch 50. Specifically, when themotor on-off relay 53 is turned on, the current is supplied from thebattery 9 to the motor 3. When the motor relay 52 is turned off, thesupply of current to the motor 3 is stopped.

FIG. 10 illustrates the engine start system of the seventh embodiment ofthe invention. A motor lead 40 extends from an inner circuit of themotor 3 (i.e., a plus (+) brush 57) and connects with the B-terminalbolt 31 of the solenoid switch 50 joined to the motor on-off relay 53through the cable wire 56. If the solenoid switch 50 is of aconventional structure, the motor lead 40 is, as illustrated in FIG. 7,connected to the M-terminal bolt 32. The motor lead 40 in thisembodiment is not connected to the M-terminal bolt 32, but to theB-terminal bolt 31. The M-terminal bolt 32 is, therefore, isolated fromthe motor circuit.

Like in the sixth embodiment, the flow of current from the battery 9 tothe motor 3 is established or blocked only by closing or opening themotor on-off relay 53 regardless of opening or closing of the maincontacts by the solenoid switch 50. Specifically, when the motor on-offrelay 53 is turned on, the current is supplied to the motor 3 from theB-terminal bolt 31 through the motor lead 40.

FIG. 11 illustrates the engine start system of the eighth embodiment ofthe invention. The solenoid switch 50 has the M-terminal bolt 32 and theB-terminal bolt 31. The cable wire 56 is connected to the M-terminalbolt 32 of the solenoid switch 50. In other words, the motor on-offrelay 53 is connected to the M-terminal bolt 32 through the cable wire56. The motor lead 40 is, like in the conventional structure of thesolenoid switch 50, connected to the M-terminal bolt 32. The B-terminalbolt 31 is, therefore, isolated from the motor circuit without beingconnected thereto.

Like in the sixth embodiment, the flow of current from the battery 9 tothe motor 3 is established or blocked only by closing or opening themotor on-off relay 53 regardless of opening or closing of the maincontacts by the solenoid switch 50. Specifically, when the motor on-offrelay 53 is turned on, the current is supplied to the motor 3 from theM-terminal bolt 32 through the motor lead 40.

In the sixth to eighth embodiments, the B-terminal bolt 31 correspondsto a first terminal bolt, as recited in claims 14 to 16, and theM-terminal bolt 32 corresponds to a second terminal bolt, as recited inclaims.

FIG. 12 illustrates the engine start system of the ninth embodiment ofthe invention. The B-terminal bolt 31 and the M-terminal bolt 32 of thesolenoid switch 50 are not connected to the motor circuit. Therefore,the solenoid switch 50 works only to thrust the pinion gear 6 away fromthe motor 3 through movement of the plunger 52, but does not function tosupply or cut the current from the battery 9 to the motor 3.

The motor on-off relay 53 is disposed in, for example, the motor circuitlocated upstream of the main contacts (i.e., the contacts 33 and 34) andfunctions to open or close relay contacts electrically to block orestablish the flow of current from the battery 9 to the motor 3. Themotor on-off relay 53 is not connected to either of the B-terminal bolt31 or the M-terminal bolt 32 of the solenoid switch 50, but joineddirectly to the motor 3.

The structure of the sixth to ninth embodiments eliminates the need fora switching function to open or close the main contacts of the solenoidswitch 50, thus permitting parts associated with the switching functionto be omitted to simplify the structure of the solenoid switch 50, whichleads to a decrease in production cost of the engine start system. Forinstance, the structure in the sixth embodiment eliminates the need forthe movable contacts 34, the plunger rod 43 supporting the movablecontacts 34, and the spring 44. In the case where the engine startsystem has the structure in which the terminal bolts 31 and 32 aredisposed on a member separate from that on which the fixed contact 33 isdisposed, the fixed contact 22 may be omitted.

The structure of the seventh embodiment may omit the M-terminal bolt 32.The structure of the eighth embodiment may omit the B-terminal bolt 31.The structure of the ninth embodiment does not connect the terminalbolts 31 and 32 to the motor circuit, thus permitting the switchingfunction as well as the terminal bolts 31 and 32 to be omitted and mayalternatively use the solenoid switch 50 equipped with the terminals 31and 32 as it is.

The solenoid switch 50 in the sixth to ninth embodiments needs not workas a switch to establish or block the supply of current to operate themotor 3, thus resulting in failure rate of the solenoid switch 50 toimprove the reliability in operation of the engine start system.

FIG. 13 illustrates an engine start system of the tenth embodiment ofthe invention which is a modification of the fifth embodiment. Theengine start system of this embodiment is identical in arrangement ofthe starter 1 equipped with the solenoid switch 50 and the motor on-offrelay 53 with the fifth embodiment, and explanation thereof in detailwill be omitted here.

The motor on-off relay 53 is designed as a normally closed type. Whenthe motor on-off sub-relay 54 is turned on to close the excitationcircuit, the motor on-off relay 53 is energized by the battery 9, sothat it is turned off to open relay contacts thereof. When the motoron-off sub-relay 54 is turned off to open the excitation circuit, themotor on-off relay 53 is deenergized to close the relay contacts.

Before the solenoid switch 50 closes the main contacts, the ECU 2 turnson the motor on-off sub-relay 54 to turn off the motor on-off relay 53and then turn off the motor on-off sub-relay 54 to turn on the motoron-off relay 53 at the second operation time. Therefore, when the maincontacts are closed by the solenoid switch 50, the motor on-off relay 53is in the off-state. The motor on-off relay 53 is kept off to maintainthe motor 3 turned off until the pinion gear 6 at least partially mesheswith the ring gear 25 or the pinion gear 6 travels to the maximummovable position and meshes with the ring gear 25. The torque producedby the motor 3 is, therefore, not transmitted to the pinion gear 6.

The use of the normally closed type of the motor on-off relay 53 permitsthe engine to be started by, for example, a manual key operation made bya vehicle operator if the ECU 2 has failed in operation. Specifically,the solenoid switch 50 is activated, as can be seen in FIG. 13, inresponse to a normal input which is produced by manual turning on of anignition switch to excite the starter relay 20 independently of the ECU2. The relay contacts of the motor on-off relay 53 are kept closed(i.e., in the on-state) at all the time. The energization of the motor 3is, thus, achieved by closing the main contacts through the operation ofthe solenoid switch 50. The structure of the engine start system of thisembodiment, as described above, permits the engine to be started by themanual key operation made by the vehicle operator, thus ensuring thehigh reliability of starting the engine.

The eleventh and twelfth embodiments of the invention will be describedbelow.

Engine start systems of the eleventh and twelfth embodiments are, likein the second embodiment, designed to produce the time lag between thefirst and second operation times using the delay circuit 46 instead ofthe ECU 2.

The delay circuit 46 of the second embodiment is installed in the enginestart system equipped with the solenoid actuator 8 which thrusts thepinion 6 and the motor relay 10 which opens or closes the main contacts,but the engine start system of this embodiment is, like in the fifthembodiment, equipped with the motor on-off relay 53 and the starter 1 inwhich the solenoid switch 50 is installed to trust the pinion gear 6 andopen or close the main contacts.

The delay circuit 46 of the eleventh embodiment is, as illustrated inFIG. 14, connected to the excitation circuit with the motor on-offsub-relay 54 and, as indicated by a dashed line, installed in the motoron-off relay 53.

The delay circuit 46 of the twelfth embodiment is, like in the eleventhembodiment, connected to the excitation circuit which supplies theexcitation current to the motor on-off relay 53, but the excitationcircuit is, as illustrated in FIG. 15, branched from a downstream sideof the starter relay 20 (i.e., closer to the solenoid switch 50) andjoined to the motor on-off relay 53 through the delay circuit 46. Thedelay circuit 46 is, like in the eleventh embodiment, installed in themotor on-off relay 53.

The motor on-off relay 53 of the eleventh and twelfth embodiments, asdescribed above, has built therein the delay circuit 46 connecting withthe excitation circuit of the motor on-off relay 53, thus eliminatingthe need for separate control systems for controlling the operations ofthe solenoid switch 50 and the motor on-off relay 53, respectively. Inother words, the engine start system is, as can be seen in FIGS. 14 and15, so designed that the ECU 2 controls the solenoid switch 50 and themotor on-off relay 53 through a single circuit line, thereby eliminatingthe need for use of a plurality of output ports of the ECU 2 andresulting in a reduction in production cost of the engine start system.

FIG. 16 illustrates an engine start system according to the thirteenthembodiment of the invention which is designed to establish engagement ofthe pinion gear 6 with the ring gear 25 and keep the motor on-off relay53 off until an engine restart request signal is inputted to the ECU 2during deceleration of the engine prior to the stop of the engine. Theengine restart request signal is a signal indicating that the abovedescribed engine restart conditions have been met and may be provided byan output from the brake sensor and/or an output from a selector levelsensor for the automatic transmission.

The engine start system is, like in the fifth embodiment, equipped withthe motor on-off relay 53 and the starter 1 in which the solenoid switch50 is installed to thrust the pinion gear 6 and the open or close themain contacts. Additionally, the ECU 2 has a delay function which is tobe performed to delay the energization of the motor on-off relay 53(i.e., the second operation time) until after the energization of thesolenoid switch 50 (i.e., the first operation time).

During deceleration of the engine prior to the stop thereof, the ECU 2turns on the starter relay 20 to activate the solenoid switch 50 to movethe pinion gear 6 and keeps the motor on-off relay 53 off, in otherwords, delays the on-operation of the motor on-off relay 53 until thepinion gear 6 meshes with the ring gear 25 at least partially or isplaced in mesh with the ring gear 25 at the maximum movable position,and the main contacts are closed, after which the engine restart requestsignal is inputted to the ECU 2.

The ECU 2 brings the pinion gear 6 into engagement with the ring gear 25before the engine restart conditions are met, that is, the enginerestart request signal is inputted thereinto and keeps such engagementuntil and after the engine stops. Afterwards, when the engine restartrequest signal is inputted, the ECU 2 turns on the motor on-off relay 53to activate the motor 3 to crank the engine. This results in a decreasedtime required to restart the engine. The pinion gear 6 is brought intoengagement with the ring gear 25 during the deceleration of the engine,thus eliminating the mechanical impact or noise which typically arisesfrom the engagement of the pinion gear 6 with the ring gear 25 when theengine is cranked.

FIG. 17 illustrates an engine start system according to the fourteenthembodiment of the invention in which the motor on-off relay 53, asreferred to in the five to thirteenth embodiments, is mounted on thestarter housing 11.

The starter 1 is a part to be installed on the engine. It is, thus,essential to assure the quality of the starter 1 against mechanicalvibrations. In order to meet such quality assurance, the motor on-offrelay 53 is secured to the starter housing 11 which is close to anengine mount and smallest in magnitude of the vibration.

Modifications of the first to thirteenth embodiments will be describedbelow.

The engine start system of the first to thirteenth embodiments works tobring the pinion gear 6 into engagement with the ring gear 25 during thedeceleration of the engine prior to the stop thereof. The engagement ofthe pinion gear 6 with the ring gear 25 when the speed of the engine isrelatively high usually results in an increase in magnitude of theimpact arising from the engagement of the pinion gear 6 with the ringgear 25. In order to alleviate this problem, the engine start system maybe designed to bring the pinion gear 6 into engagement with the ringgear 25 when the speed of the engine is lower than a preselected idlespeed (e.g., 300 rpm) during the deceleration of the engine prior to thestop thereof.

In the first embodiment, the solenoid actuator 8 and the motor relay 10are aligned in series in the axial direction thereof, but they mayalternatively be disposed independently of each other. For instance,they may be disposed out of alignment with each other in the axialdirection of the motor 3.

The engine start systems of the sixth to eighth and tenth to twelfthembodiments have the motor on-off relay 53 which is disposed in themotor circuit and located upstream of the main contacts of the solenoidswitch 50, but may alternatively be designed to have the motor on-offrelay 53 disposed downstream of the main contacts, that is, between theM-terminal bolt 32 of the solenoid switch 50 and the motor 3 (betweenthe B-terminal bolt 31 and the motor 3 in the seventh embodiment).

The engine start system of each of the first to thirteenth embodimentsis mounted in the automotive vehicle equipped with the idle stop system,but however, the present invention may be used with automotive vehicleswhich are not equipped with the idle stop system. For example, theengine start systems of the invention may be used to restart the enginebefore it stops completely after the ignition switch is turned off invehicles in which the engine is started by the starter 1 in response toturning on of the ignition switch and stopped in response to turning offof the ignition switch.

While the present invention has been disclosed in terms of the preferredembodiments in order to facilitate better understanding thereof, itshould be appreciated that the invention can be embodied in various wayswithout departing from the principle of the invention. Therefore, theinvention should be understood to include all possible embodiments andmodifications to the shown embodiments witch can be embodied withoutdeparting from the principle of the invention as set forth in theappended claims.

1. An engine start system comprising: a motor which is energized bysupply of electric power from a battery through a motor circuit toproduce torque; an output shaft which rotates when subjected to thetorque, as produced by said motor; a pinion gear through which thetorque, as produced by said motor, is transmitted to a ring gear coupledto an engine; a pinion movable body which is movable along said outputshaft together with said pinion gear; a pinion actuator working to movesaid pinion movable body to the ring gear; a switching mechanism workingto open or close main contacts installed in the motor circuit to cut orsupply the electric power from the battery to said motor; a controllerwhich controls operations of said pinion actuator and said switchingmechanism when the engine is restarted during deceleration of the engineprior to stop of the engine; and delay means for delaying a secondoperation time that is a time when said switching mechanism is to beactivated to close the main contacts until after a first operation timethat is a time when said pinion actuator is to be activated to move saidpinion movable body when the engine is restarted, said delay meansproducing a time lag between the first and second operation times so asto close the main contacts through said switching mechanism to supplythe electric power to said motor after said pinion movable body is movedby said pinion actuator to shift the pinion gear from a rest position toa gear engageble position where said pinion gear is engageble with thering gear, and then said pinion gear engages the ring gear.
 2. An enginestart system as set forth in claim 1, wherein said delay means sets thetime lag between the first and second operation times to 30 ms. or more.3. An engine start system as set forth in claim 1, wherein said pinionactuator is implemented by a solenoid actuator which produces a firstelectromagnet, and said switching mechanism is implemented by a motoron-off switch which produces a second electromagnet, and wherein saidcontroller is designed to control operations of the solenoid actuatorand the motor on-off switch independently of each other and hasinstalled therein a delay function which makes up said delay means. 4.An engine start system as set forth in claim 1, wherein said pinionactuator is implemented by a solenoid actuator which produces a firstelectromagnet, and said switching mechanism is implemented by a motoron-off switch which produces a second electromagnet, wherein saidcontroller is designed to control operations of the solenoid actuatorand the motor on-off switch independently of each other, and whereinsaid delay means is implemented by a delay circuit connected to anexcitation circuit which works to excite the motor on-off switch.
 5. Anengine start system as set forth in claim 3, wherein said controllerchanges the time lag between when the engine is requested to berestarted during the deceleration of the engine and when the engine isrequested to be restarted after a complete stop of the engine.
 6. Anengine start system as set forth in claim 3, wherein said solenoidactuator and said motor on-off switch are aligned in series with eachother in an axial direction thereof.
 7. An engine start system as setforth in claim 6, wherein said solenoid actuator and said motor on-offswitch have casings, respectively, which are arrayed integrally in theaxial direction and constitute a magnetic circuit.
 8. An engine startsystem as set forth in claim 1, further comprising a magnetic coilproducing an electromagnet when energized, a plunger which is movablealong an inner periphery of said magnetic coil in an axial directionthereof, and a single electromagnetic switch designed to perform both anoperation of said pinion actuator and an operation of the switchingmechanism following movement of said plunger, and wherein the time lagis provided by a plunger stroke that is a distance which said plungermoves from a time when said plunger starts to be moved by attraction, asproduced by the electromagnetic, until the main contacts are closed. 9.An engine start system as set forth in claim 1, wherein the engine startsystem is installed in a vehicle equipped with an idle stop systemworking to stop and restart the engine automatically.
 10. An enginestart system comprising: a motor which is energized by supply ofelectric power from a battery through a motor circuit to produce torque;an output shaft which rotates when subjected to the torque, as producedby said motor; a pinion gear through which the torque, as produced bysaid motor, is transmitted to a ring gear coupled to an engine; a pinionmovable body which is movable along said output shaft together with saidpinion gear; a pinion actuator working to move said pinion movable bodyto the ring gear; a switching mechanism working to open or close maincontacts installed in the motor circuit to cut or supply the electricpower from the battery to said motor; a controller which controlsoperations of said pinion actuator and said switching mechanism when theengine is restarted during deceleration of the engine prior to stop ofthe engine; and delay means for delaying a second operation time that isa time when said switching mechanism is to be activated to close themain contacts until after a first operation time that is a time whensaid pinion actuator is to be activated to move said pinion movable bodywhen the engine is restarted, said delay means producing a time lagbetween the first and second operation times so as to close the maincontacts through said switching mechanism to supply the electric powerto said motor after said pinion movable body is moved by said pinionactuator to advance the pinion gear from a rest position to a maximummovable position where engagement of said pinion gear with the ring gearis to be achieved, and then said pinion gear has engaged the ring gear.11. An engine start system as set forth in claim 10, wherein said delaymeans sets the time lag between the first and second operation times to30 ms. or more.
 12. An engine start system as set forth in claim 10,wherein said pinion actuator is implemented by a solenoid actuator whichproduces a first electromagnet, and said switching mechanism isimplemented by a motor on-off switch which produces a secondelectromagnet, and wherein said controller is designed to controloperations of the solenoid actuator and the motor on-off switchindependently of each other and has installed therein a delay functionwhich makes up said delay means.
 13. An engine start system as set forthin claim 10, wherein said pinion actuator is implemented by a solenoidactuator which produces a first electromagnet, and said switchingmechanism is implemented by a motor on-off switch which produces asecond electromagnet, wherein said controller is designed to controloperations of the solenoid actuator and the motor on-off switchindependently of each other, and wherein said delay means is implementedby a delay circuit connected to an excitation circuit which works toexcite the motor on-off switch.
 14. An engine start system as set forthin claim 12, wherein said controller changes the time lag between whenthe engine is requested to be restarted during the deceleration of theengine and when the engine is requested to be restarted after a completestop of the engine.
 15. An engine start system as set forth in claim 12,wherein said solenoid actuator and said motor on-off switch are alignedin series with each other in an axial direction thereof.
 16. An enginestart system as set forth in claim 15, wherein said solenoid actuatorand said motor on-off switch have casings, respectively, which arearrayed integrally in the axial direction and constitute a magneticcircuit.
 17. An engine start system as set forth in claim 10, furthercomprising a magnetic coil producing an electromagnet when energized, aplunger which is movable along an inner periphery of said magnetic coilin an axial direction thereof, and a single electromagnetic switchdesigned to perform both an operation of said pinion actuator and anoperation of the switching mechanism following movement of said plunger,and wherein the time lag is provided by a plunger stroke that is adistance which said plunger moves from a time when said plunger startsto be moved by attraction, as produced by the electromagnetic, until themain contacts are closed.
 18. An engine start system as set forth inclaim 10, wherein the engine start system is installed in a vehicleequipped with an idle stop system working to stop and restart the engineautomatically.
 19. An engine start system comprising: a motor which isenergized by supply of electric power from a battery through a motorcircuit to produce torque; an output shaft which rotates when subjectedto the torque, as produced by said motor; a pinion gear through whichthe torque, as produced by said motor, is transmitted to a ring gearcoupled to an engine; a pinion movable body which is movable along saidoutput shaft together with said pinion gear; a pinion solenoid actuatorwhich produce magnetic attraction to thrust said pinion movable bodytoward the ring gear; a motor on-off switch which opens or closes maincontacts installed in the motor circuit to cut or supply the electricpower to said motor; a first relay disposed in an excitation circuitwhich supplies electric power from the battery to said pinion solenoidactuator; a second relay disposed in an excitation circuit whichsupplies electric power from the battery to said motor on-off switch; acontroller which electrically controls an operation of said pinionsolenoid actuator through said first relay and an operation of saidmotor on-off switch through said second relay when the engine isrestarted during deceleration of the engine prior to stop of the engine;a delay circuit which delays a second operation time that is a time whensaid second relay is to be energized until after a first operation timethat is a time when said first relay is to be energized when the engineis restarted; and a single electric wire connecting with an output portof said controller, said electric wire having a first relay branch lineleading to said first relay and a second relay branch line leading tosaid second relay through said delay circuit, wherein said delay circuitproduces a time lag between the first and second operation times so asto close said motor on-off switch to supply the electric power to saidmotor after said pinion gear is moved by said pinion solenoid actuatorfrom a rest position to a gear engageble position where said pinion gearis engageble with the ring gear and then engages the ring gear or fromthe rest portion to a maximum movable position where engagement of saidpinion gear with the ring gear is to be established and then engages thering gear.
 20. An engine start system as set forth in claim 19, whereinthe engine start system is installed in a vehicle equipped with an idlestop system working to stop and restart the engine automatically.
 21. Anengine start system comprising: a motor which is energized by supply ofelectric power from a battery through a motor circuit to produce torque;an output shaft which rotates when subjected to the torque, as producedby said motor; a pinion gear through which the torque, as produced bysaid motor, is transmitted to a ring gear coupled to an engine; a pinionmovable body which is movable along said output shaft together with saidpinion gear; a solenoid switch which works to produce a magneticattraction to attract a plunger to thrust said pinion gear toward thering gear and also open or close main contacts installed in the motorcircuit interlocking with movement of the plunger for cutting orsupplying the electric power to said motor; a motor on-off relay whichhas relay contacts disposed in the motor circuit and opens or closes therelay contacts electrically; a controller which electrically controls anoperation of said solenoid switch and an operation of said motor on-offrelay when the engine is restarted during deceleration of the engineprior to stop of the engine; and delay means for delaying a secondoperation time that is a time when said motor on-off relay is to beenergized until after a first operation time that is a time when saidsolenoid switch is to be energized when the engine is restarted, saiddelay means producing a time lag between the first and second operationtimes so as to turn on said motor on-off relay to supply the electricpower to said motor after said pinion gear is moved by said solenoidswitch to the ring gear and then engages the ring gear at leastpartially or to a maximum movable position where engagement of saidpinion gear with the ring gear is to be established and then engages thering gear, and after the main contacts are closed.
 22. An engine startsystem as set forth in claim 21, wherein said delay means is implementedby a delay circuit connected to an excitation circuit which works toexcite said motor on-off relay and is built in said motor on-off relay.23. An engine start system as set forth in claim 21, wherein said motoron-off relay has the relay contacts disposed upstream of the maincontacts of the motor circuit.
 24. An engine start system as set forthin claim 21, wherein said motor on-off relay is installed on a housingof a starter in which said motor is installed.
 25. An engine startsystem as set forth in claim 21, wherein the engine start system isinstalled in a vehicle equipped with an idle stop system working to stopand restart the engine automatically.
 26. An engine start systemcomprising: a motor which is energized by supply of electric power froma battery through a motor circuit to produce torque; an output shaftwhich rotates when subjected to the torque, as produced by said motor; apinion gear through which the torque, as produced by said motor, istransmitted to a ring gear coupled to an engine; a pinion movable bodywhich is movable along said output shaft together with said pinion gear;a solenoid switch which works to produce a magnetic attraction toattract a plunger to thrust said pinion gear toward the ring gear andhas an external terminal which is connected to the motor circuit andthrough which the electric power is supplied to said motor; a motoron-off relay which has relay contacts disposed in the motor circuit andopens or closes the relay contacts electrically; a controller whichelectrically controls an operation of said solenoid switch and anoperation of said motor on-off relay when the engine is restarted duringdeceleration of the engine prior to stop of the engine; and delay meansfor delaying a second operation time that is a time when said motoron-off relay is to be energized until after a first operation time thatis a time when said solenoid switch is to be energized on when theengine is restarted, said delay means producing a time lag between thefirst and second operation times so as to turn on said motor on-offrelay to supply the electric power to said motor after said pinion gearis moved by said solenoid switch to the ring gear and then engages thering gear at least partially or to a maximum movable position whereengagement of said pinion gear with the ring gear is to be establishedand then engages the ring gear.
 27. An engine start system as set forthin claim 26, wherein said solenoid switch has a first terminal bolt anda second terminal bolt, the first terminal bolt serving as said externalterminal, the second terminal bolt connecting with said motor through amotor lead, the first and second terminal bolts being connectedelectrically through a terminal-to-terminal connector.
 28. An enginestart system as set forth in claim 26, wherein said solenoid switch hasa first terminal bolt and a second terminal bolt, the first terminalbolt serving as said external terminal connecting with said motorthrough a motor lead, the second terminal bolt being isolated from saidmotor circuit.
 29. An engine start system as set forth in claim 26,wherein said solenoid switch has a first terminal bolt and a secondterminal bolt, the first terminal bolt being isolated from the motorcircuit, the second terminal bolt serving as said external terminalconnecting with said motor through a motor lead.
 30. An engine startsystem as set forth in claim 26, wherein said motor on-off relay has therelay contacts in said motor circuit upstream of said external terminal.31. An engine start system as set forth in claim 26, wherein the enginestart system is installed in a vehicle equipped with an idle stop systemworking to stop and restart the engine automatically. 32-35. (canceled)36. An engine start system comprising: a motor which is energized bysupply of electric power from a battery through a motor circuit toproduce torque; an output shaft which rotates when subjected to thetorque, as produced by said motor; a pinion gear through which thetorque, as produced by said motor, is transmitted to a ring gear coupledto an engine; a pinion movable body which is movable along said outputshaft together with said pinion gear; a solenoid switch which works toproduce a magnetic attraction to attract a plunger to thrust said piniongear toward the ring gear and also open or close main contacts installedin the motor circuit interlocking with movement of the plunger forcutting or supplying the electric power to said motor; a normally closedtype of motor on-off relay which has relay contacts disposed in themotor circuit, when deenergized, said motor on-off relay keeping therelay contacts closed; a starter relay which is disposed in anexcitation circuit working to supply an excitation current to saidsolenoid switch from the battery; a motor on-off sub-relay which isdisposed in an excitation circuit working to supply an excitationcurrent to said motor on-off relay from the battery; a controller whichelectrically controls an operation of said solenoid switch through saidstarter relay and an operation of said motor on-off relay through saidmotor on-off sub-relay when the engine is restarted during decelerationof the engine prior to stop of the engine; and delay means for delayinga second operation time that is a time when said motor on-off relay isto be energized until after a first operation time that is a time whensaid solenoid switch is to be energized on when the engine is restarted,said delay means producing a time lag between the first and secondoperation times so as to turn on said motor on-off relay to supply theelectric power to said motor after said pinion gear is moved by saidsolenoid switch to the ring gear and then engages the ring gear at leastpartially or to a maximum movable position where engagement of saidpinion gear with the ring gear is to be established and then engages thering gear, and after the main contacts are closed, wherein saidcontroller energizes said motor on-off sub-relay to open said motoron-off relay before said main contacts are closed by the solenoid switchand then closes said motor on-off relay following the first operationtime.
 37. An engine start system as set forth in claim 36, wherein saidmotor on-off relay has the relay contacts disposed upstream of the maincontacts of the motor circuit.
 38. An engine start system as set forthin claim 36, wherein said motor on-off relay is installed on a housingof a starter in which said motor is installed.
 39. An engine startsystem as set forth in claim 36, wherein the engine start system isinstalled in a vehicle equipped with an idle stop system working to stopand restart the engine automatically.
 40. An engine start systemcomprising: a motor which is energized by supply of electric power froma battery through a motor circuit to produce torque; an output shaftwhich rotates when subjected to the torque, as produced by said motor; apinion gear through which the torque, as produced by said motor, istransmitted to a ring gear coupled to an engine; a pinion movable bodywhich is movable along said output shaft together with said pinion gear;a solenoid switch which works to produce a magnetic attraction toattract a plunger to thrust said pinion gear toward the ring gear andalso open or close main contacts installed in the motor circuitinterlocking with movement of the plunger for cutting or supplying theelectric power to said motor; a motor on-off relay which has relaycontacts disposed in the motor circuit and opens or closes the relaycontacts electrically; and a controller which electrically controls anoperation of said solenoid switch and an operation of said motor on-offrelay, during deceleration of the engine prior to stop of the engine,said controller energizing said solenoid switch to move said pinion gearand delaying the operation of said motor on-off relay until after saidpinion bear engages the ring gear at least partially or said pinion ismoved to a maximum movable position wherein engagement of the piniongear with the ring gear is to be established and then engages the ringgear, and the main contacts are closed, after which an engine restartrequest signal is inputted to said controller.
 41. An engine startsystem as set forth in claim 40, wherein said motor on-off relay has therelay contacts disposed upstream of the main contacts of the motorcircuit.
 42. An engine start system as set forth in claim 40, whereinsaid motor on-off relay is installed on a housing of a starter in whichsaid motor is installed.
 43. An engine start system as set forth inclaim 40, wherein the engine start system is installed in a vehicleequipped with an idle stop system working to stop and restart the engineautomatically.
 44. An engine start system comprising: a motor which isenergized by supply of electric power from a battery through a motorcircuit to produce torque; an output shaft which rotates when subjectedto the torque, as produced by said motor; a pinion gear through whichthe torque, as produced by said motor, is transmitted to a ring gearcoupled to an engine; a pinion movable body which is movable along saidoutput shaft together with said pinion gear; a pinion actuator workingto move said pinion movable body to the ring gear; a switching mechanismworking to open or close main contacts installed in the motor circuit tocut or supply the electric power from the battery to said motor; acontroller which controls operations of said pinion actuator and saidswitching mechanism when the engine is restarted during deceleration ofthe engine prior to stop of the engine; and delay means for electricallyor mechanically delaying a second operation time that is a time whensaid switching mechanism is to be activated to close the main contactsuntil after a first operation time that is a time when said pinionactuator is to be activated to move said pinion movable body when theengine is restarted, said delay means producing one of a first time lagand a second time lag between the first and second operation times so asto close the main contacts through said switching mechanism to supplythe electric power to said motor after said pinion movable body is movedby said pinion actuator to shift the pinion gear from a rest position toa gear engageble position where said pinion gear is engageble with thering gear, and then said pinion gear engages the ring gear, said delaymeans selectively setting the first time lag when it is required torestart the engine after complete stop of rotation of the engine and thesecond lag time when it is required to restart the engine beforecomplete stop of rotation of the engine, the second time lag beinglonger than or equal to the first lag time.
 45. An engine start systemas set forth in claim 44, wherein first time lag which is provided whenit is required to restart the engine after complete stop of rotation ofthe engine is different from the second time lag which is provided whenit is required to restart the engine before complete stop of rotation ofthe engine.
 46. An engine start system as set forth in claim 44, whereinthe second time lag is 30 ms. or more.
 47. An engine start system as setforth in claim 44, wherein said pinion actuator is implemented by asolenoid actuator which produces a first electromagnet when energized toattract a plunger to move the pinion movable body toward the ring gear,wherein said switching mechanism is implemented by a motor on-off switchwhich produces a second electromagnet when energized to attract amovable core to open or close the main contacts, and wherein saidcontroller is designed to control operations of the solenoid actuatorand the motor on-off switch independently of each other and hasinstalled therein a delay function which makes up said delay means.